Programming language: Go
License: MIT License
Tags: Communication systems     Social Networks and Forums    
Latest version: v1.6.0

remark42 alternatives and similar software solutions

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Remark42 Build Status Go Report Card Coverage Status codecov

Remark42 is a self-hosted, lightweight and simple (yet functional) comment engine, which doesn't spy on users. It can be embedded into blogs, articles, or any other place where readers add comments.

  • Social login via Google, Twitter, Facebook, Microsoft, GitHub, Yandex and Telegram
  • Login via email
  • Optional anonymous access
  • Multi-level nested comments with both tree and plain presentations
  • Import from Disqus and WordPress
  • Markdown support with friendly formatter toolbar
  • Moderator can remove comments and block users
  • Voting, pinning and verification system
  • Sortable comments
  • Images upload with drag-and-drop
  • Extractor for recent comments, cross-post
  • RSS for all comments and each post
  • Telegram, Slack and email notifications for Admins (get notified for each new comment)
  • Email and Telegram notifications for users (get notified when someone responds to your comment)
  • Export data to JSON with automatic backups
  • No external databases, everything embedded in a single data file
  • Fully dockerized and can be deployed in a single command
  • Self-contained executable can be deployed directly to Linux, Windows and macOS
  • Clean, lightweight and customizable UI with white and dark themes
  • Multi-site mode from a single instance
  • Integration with automatic SSL (direct and via nginx-le)
  • Privacy focused

Demo site available with all authentication methods, including email auth and anonymous access.


Comments example: [](screenshots/comments.png)

For admin screenshots see Admin UI wiki



With Docker

this is the recommended way to run Remark42

  • copy provided docker-compose.yml and customize for your needs
  • make sure you don't keep ADMIN_PASSWD=something... for any non-development deployments
  • pull prepared images from the Docker Hub and start - docker-compose pull && docker-compose up -d
  • alternatively compile from the sources - docker-compose build && docker-compose up -d

Without Docker

  • download archive for stable release
  • unpack with gunzip (Linux, macOS) or with zip (Windows)
  • run as remark42.{os}-{arch} server {parameters...}, i.e. remark42.linux-amd64 server --secret=12345 --url=
  • alternatively compile from the sources - make OS=[linux|darwin|windows] ARCH=[amd64,386,arm64,arm]


Command line Environment Default Description
url REMARK_URL URL to Remark42 server, required
secret SECRET shared secret key used to sign JWT, should be a random, long, hard-to-guess string, required
site SITE remark site name(s), multi
store.type STORE_TYPE bolt type of storage, bolt or rpc
store.bolt.path STORE_BOLT_PATH ./var path to data directory
store.bolt.timeout STORE_BOLT_TIMEOUT 30s boltdb access timeout
admin.shared.id ADMIN_SHARED_ID admin IDs (list of user IDs), multi
admin.shared.email ADMIN_SHARED_EMAIL [email protected]${REMARK_URL} admin emails, multi
backup BACKUP_PATH ./var/backup backups location
max-back MAX_BACKUP_FILES 10 max backup files to keep
cache.type CACHE_TYPE mem type of cache, redis_pub_sub or mem or none
cache.redis_addr CACHE_REDIS_ADDR address of redis PubSub instance, turn redis_pub_sub cache on for distributed cache
cache.max.items CACHE_MAX_ITEMS 1000 max number of cached items, 0 - unlimited
cache.max.value CACHE_MAX_VALUE 65536 max size of cached value, 0 - unlimited
cache.max.size CACHE_MAX_SIZE 50000000 max size of all cached values, 0 - unlimited
avatar.type AVATAR_TYPE fs type of avatar storage, fs, bolt, or uri
avatar.fs.path AVATAR_FS_PATH ./var/avatars avatars location for fs store
avatar.bolt.file AVATAR_BOLT_FILE ./var/avatars.db file name for bolt store
avatar.uri AVATAR_URI ./var/avatars avatar store uri
avatar.rsz-lmt AVATAR_RSZ_LMT 0 (disabled) max image size for resizing avatars on save
image.type IMAGE_TYPE fs type of image storage, fs, bolt
image.max-size IMAGE_MAX_SIZE 5000000 max size of image file
image.fs.path IMAGE_FS_PATH ./var/pictures permanent location of images
image.fs.staging IMAGE_FS_STAGING ./var/pictures.staging staging location of images
image.fs.partitions IMAGE_FS_PARTITIONS 100 number of image partitions
image.bolt.file IMAGE_BOLT_FILE /var/pictures.db images bolt file location
image.resize-width IMAGE_RESIZE_WIDTH 2400 width of resized image
image.resize-height IMAGE_RESIZE_HEIGHT 900 height of resized image
auth.ttl.jwt AUTH_TTL_JWT 5m jwt TTL
auth.ttl.cookie AUTH_TTL_COOKIE 200h cookie TTL
auth.send-jwt-header AUTH_SEND_JWT_HEADER false send JWT as a header instead of cookie
auth.same-site AUTH_SAME_SITE default set same site policy for cookies (default, none, lax or strict)
auth.google.cid AUTH_GOOGLE_CID Google OAuth client ID
auth.google.csec AUTH_GOOGLE_CSEC Google OAuth client secret
auth.facebook.cid AUTH_FACEBOOK_CID Facebook OAuth client ID
auth.facebook.csec AUTH_FACEBOOK_CSEC Facebook OAuth client secret
auth.microsoft.cid AUTH_MICROSOFT_CID Microsoft OAuth client ID
auth.microsoft.csec AUTH_MICROSOFT_CSEC Microsoft OAuth client secret
auth.github.cid AUTH_GITHUB_CID GitHub OAuth client ID
auth.github.csec AUTH_GITHUB_CSEC GitHub OAuth client secret
auth.twitter.cid AUTH_TWITTER_CID Twitter Consumer API Key
auth.twitter.csec AUTH_TWITTER_CSEC Twitter Consumer API Secret key
auth.telegram AUTH_TELEGRAM Enable Telegram auth (telegram.token must be present)
auth.yandex.cid AUTH_YANDEX_CID Yandex OAuth client ID
auth.yandex.csec AUTH_YANDEX_CSEC Yandex OAuth client secret
auth.dev AUTH_DEV false local OAuth2 server, development mode only
auth.anon AUTH_ANON false enable anonymous login
auth.email.enable AUTH_EMAIL_ENABLE false enable auth via email
auth.email.from AUTH_EMAIL_FROM email from
auth.email.subj AUTH_EMAIL_SUBJ remark42 confirmation email subject
auth.email.content-type AUTH_EMAIL_CONTENT_TYPE text/html email content type
auth.email.template AUTH_EMAIL_TEMPLATE none (predefined) custom email message template file
notify.users NOTIFY_USERS none type of user notifications (Telegram, email)
notify.admins NOTIFY_ADMINS none type of admin notifications (Telegram, Slack and/or email)
notify.queue NOTIFY_QUEUE 100 size of notification queue
notify.telegram.chan NOTIFY_TELEGRAM_CHAN Telegram channel
notify.slack.token NOTIFY_SLACK_TOKEN Slack token
notify.slack.chan NOTIFY_SLACK_CHAN general Slack channel
notify.email.fromAddress NOTIFY_EMAIL_FROM from email address
notify.email.verification_subj NOTIFY_EMAIL_VERIFICATION_SUBJ Email verification verification message subject
telegram.token TELEGRAM_TOKEN Telegram token (used for auth and Telegram notifications)
telegram.timeout TELEGRAM_TIMEOUT 5s Telegram connection timeout
smtp.host SMTP_HOST SMTP host
smtp.port SMTP_PORT SMTP port
smtp.username SMTP_USERNAME SMTP user name
smtp.password SMTP_PASSWORD SMTP password
smtp.tls SMTP_TLS enable TLS for SMTP
smtp.timeout SMTP_TIMEOUT 10s SMTP TCP connection timeout
ssl.type SSL_TYPE none none-HTTP, static-HTTPS, auto-HTTPS + le
ssl.port SSL_PORT 8443 port for HTTPS server
ssl.cert SSL_CERT path to cert.pem file
ssl.key SSL_KEY path to key.pem file
ssl.acme-location SSL_ACME_LOCATION ./var/acme dir where obtained le-certs will be stored
ssl.acme-email SSL_ACME_EMAIL admin email for receiving notifications from LE
max-comment MAX_COMMENT_SIZE 2048 comment's size limit
max-votes MAX_VOTES -1 votes limit per comment, -1 - unlimited
votes-ip VOTES_IP false restrict votes from the same IP
anon-vote ANON_VOTE false allow voting for anonymous users, require VOTES_IP to be enabled as well
votes-ip-time VOTES_IP_TIME 5m same IP vote restriction time, 0s - unlimited
low-score LOW_SCORE -5 low score threshold
critical-score CRITICAL_SCORE -10 critical score threshold
positive-score POSITIVE_SCORE false restricts comment's score to be only positive
restricted-words RESTRICTED_WORDS words banned in comments (can use *), multi
restricted-names RESTRICTED_NAMES names prohibited to use by the user, multi
edit-time EDIT_TIME 5m edit window
admin-edit ADMIN_EDIT false unlimited edit for admins
read-age READONLY_AGE read-only age of comments, days
image-proxy.http2https IMAGE_PROXY_HTTP2HTTPS false enable HTTP->HTTPS proxy for images
image-proxy.cache-external IMAGE_PROXY_CACHE_EXTERNAL false enable caching external images to current image storage
emoji EMOJI false enable emoji support
simple-view SIMPLE_VIEW false minimized UI with basic info only
proxy-cors PROXY_CORS false disable internal CORS and delegate it to proxy
allowed-hosts ALLOWED_HOSTS enable all limit hosts/sources allowed to embed comments
address REMARK_ADDRESS all interfaces web server listening address
port REMARK_PORT 8080 web server port
web-root REMARK_WEB_ROOT ./web web server root directory
update-limit UPDATE_LIMIT 0.5 updates/sec limit
admin-passwd ADMIN_PASSWD none (disabled) password for admin basic auth
dbg DEBUG false debug mode
  • command line parameters are long-form --<key>=value, i.e. --site=https://demo.remark42.com
  • multi parameters separated by , in the environment or repeated with command line key, like --site=s1 --site=s2 ...
  • required parameters have to be presented in the environment or provided in the command line
Deprecated parameters

The following list of command-line options is deprecated and will be removed in 2 minor releases or 1 major release (whichever is closer) from the version in which they were deprecated. After Remark42 version update, please check the startup log once for deprecation warnings to avoid trouble with unrecognized command-line options in the future.

Deprecated options

Command line Replacement Environment Replacement Default Description Deprecation version
auth.email.host smtp.host AUTH_EMAIL_HOST SMTP_HOST smtp host 1.5.0
auth.email.port smtp.port AUTH_EMAIL_PORT SMTP_PORT smtp port 1.5.0
auth.email.user smtp.username AUTH_EMAIL_USER SMTP_USERNAME smtp user name 1.5.0
auth.email.passwd smtp.password AUTH_EMAIL_PASSWD SMTP_PASSWORD smtp password 1.5.0
auth.email.tls smtp.tls AUTH_EMAIL_TLS SMTP_TLS false enable TLS 1.5.0
auth.email.timeout smtp.timeout AUTH_EMAIL_TIMEOUT SMTP_TIMEOUT 10s smtp timeout 1.5.0
img-proxy image-proxy.http2https IMG_PROXY IMAGE_PROXY_HTTP2HTTPS false enable HTTP->HTTPS proxy for images 1.5.0
notify.type notify.admins, notify.users NOTIFY_TYPE NOTIFY_ADMINS, NOTIFY_USERS 1.9.0
notify.email.notify_admin notify.admins=email NOTIFY_EMAIL_ADMIN NOTIFY_ADMINS=email 1.9.0
notify.telegram.token telegram.token NOTIFY_TELEGRAM_TOKEN TELEGRAM_TOKEN Telegram token 1.9.0
notify.telegram.timeout telegram.timeout NOTIFY_TELEGRAM_TIMEOUT TELEGRAM_TIMEOUT Telegram timeout 1.9.0
Required parameters

Most of the parameters have sane defaults and don't require customization. There are only a few parameters the user has to define:

  1. SECRET - secret key, can be any long and hard-to-guess string
  2. REMARK_URL - URL pointing to your Remark42 server, i.e. https://demo.remark42.com
  3. At least one pair of AUTH_<PROVIDER>_CID and AUTH_<PROVIDER>_CSEC defining OAuth2 provider(s)

The minimal docker-compose.yml has to include all required parameters:

version: '2'

    image: umputun/remark42:latest
    restart: always
    container_name: "remark42"
      - REMARK_URL=https://demo.remark42.com  # URL pointing to your Remark42 server
      - SITE=YOUR_SITE_ID                     # site ID, same as used for `site_id`, see "Setup on your website"
      - SECRET=abcd-123456-xyz-$%^&           # secret key
      - AUTH_GITHUB_CID=12345667890           # OAuth2 client ID
      - AUTH_GITHUB_CSEC=abcdefg12345678      # OAuth2 client secret
      - ./var:/srv/var                        # persistent volume to store all Remark42 data

Quick installation test

To verify if Remark42 has been properly installed, check a demo page at ${REMARK_URL}/web URL. Make sure to include remark site ID to ${SITE} list.

Register OAuth2 providers

Authentication handled by external providers. You should setup OAuth2 for all (or some) of them to allow users to make comments. It is not mandatory to have all of them, but at least one should be correctly configured.

Facebook Auth provider
  1. From https://developers.facebook.com select "My Apps"/"Add a new App"
  2. Set "Display Name" and "Contact email"
  3. Choose "Facebook Login" and then "Web"
  4. Set "Site URL" to your domain, e.g.: https://remark42.mysite.com
  5. Under "Facebook login"/"Settings" fill "Valid OAuth redirect URIs" with your callback URL constructed as domain + /auth/facebook/callback
  6. Select "App Review" and turn public flag on. This step may ask you to provide a link to your privacy policy
GitHub Auth provider
  1. Create a new "OAuth App": https://github.com/settings/developers
  2. Fill "Application Name" and "Homepage URL" for your site
  3. Under "Authorization callback URL" enter the correct URL constructed as domain + /auth/github/callback, i.e. https://remark42.mysite.com/auth/github/callback
  4. Take note of the Client ID and Client Secret
Google Auth provider
  1. Create a new project: https://console.cloud.google.com/projectcreate
  2. Choose the new project from the top right project dropdown (only if another project is selected)
  3. In the project Dashboard center pane, choose "API Manager"
  4. In the left Nav pane, choose "Credentials"
  5. In the center pane, choose "OAuth consent screen" tab. Fill in "Product name shown to users" and hit save
  6. In the center pane, choose "Credentials" tab
    • Open the "New credentials" drop down
    • Choose "OAuth client ID"
    • Choose "Web application"
    • Application name is freeform, choose something appropriate
    • Authorized origins is your domain, e.g.: https://remark42.mysite.com
    • Authorized redirect URIs is the location of OAuth2/callback constructed as domain + /auth/google/callback, e.g.: https://remark42.mysite.com/auth/google/callback
    • Choose "Create"
  7. Take note of the Client ID and Client Secret

instructions for Google OAuth2 setup borrowed from oauth2_proxy

Microsoft Auth provider
  1. Register a new application using the Azure portal
  2. Under "Authentication/Platform configurations/Web" enter the correct URL constructed as domain + /auth/microsoft/callback, i.e. https://example.mysite.com/auth/microsoft/callback
  3. In "Overview" take note of the Application (client) ID
  4. Choose the new project from the top right project dropdown (only if another project is selected)
  5. Select "Certificates & secrets" and click on "+ New Client Secret"
Telegram Auth Provider
  1. Contact @BotFather and follow his instructions to create your own bot (call it, for example, "My site auth bot")
  2. Write down resulting token as TELEGRAM_TOKEN into remark42 config, and also set AUTH_TELEGRAM to true to enable telegram auth for your users.
Twitter Auth provider
  1. Create a new Twitter application https://developer.twitter.com/en/apps
  2. Fill App name, Description and URL of your site
  3. In the field Callback URLs enter the correct URL of your callback handler, e.g. domain + /auth/twitter/callback
  4. Under Key and tokens take note of the Consumer API Key and Consumer API Secret key. Those will be used as AUTH_TWITTER_CID and AUTH_TWITTER_CSEC
Yandex Auth provider
  1. Create a new "OAuth App": https://oauth.yandex.com/client/new
  2. Fill "App name" for your site
  3. Under Platforms select "Web services" and enter "Callback URI #1" constructed as domain + /auth/yandex/callback, i.e. https://remark42.mysite.com/auth/yandex/callback
  4. Select Permissions. You need the following permissions only from the "Yandex.Passport API" section:
    • Access to the user avatar
    • Access to username, first name and surname, gender
  5. Fill out the rest of the fields if needed
  6. Take note of the ID and Password

For more details refer to Yandex OAuth and Yandex.Passport API documentation.

Anonymous Auth provider

Optionally, anonymous access can be turned on. In this case, an extra anonymous provider will allow logins without any social login with any name satisfying 2 conditions:

  • name should be at least 3 characters long
  • name has to start from the letter and contains letters, numbers, underscores and spaces only

Importing comments

Remark42 supports importing comments from Disqus, WordPress, or native backup format. All imported comments have an Imported field set to true.

Initial import from Disqus
  1. Disqus provides an export of all comments on your site in a gzipped file. This option is available in your Moderation panel at Disqus Admin > Setup > Export. The export will be sent into a queue and then emailed to the address associated with your account once it's ready. Direct link to export will be something like https://<siteud>.disqus.com/admin/discussions/export/. See importing-exporting for more details
  2. Move this file to your Remark42 host within ./var and extract, i.e. gunzip <disqus-export-name>.xml.gz
  3. Run import command - docker exec -it remark42 import -p disqus -f /srv/var/{disqus-export-name}.xml -s {your site ID}
Initial import from WordPress
  1. Use that instruction to export comments to file using standard WordPress functionality
  2. Move this file to your Remark42 host within ./var
  3. Run import command - docker exec -it remark42 import -p wordpress -f /srv/var/{wordpress-export-name}.xml -s {your site ID}

Backup and restore

Automatic backups

Remark42 by default makes daily backup files under ${BACKUP_PATH} (default ./var/backup). Backups kept up to ${MAX_BACKUP_FILES} (default 10). Each backup file contains exported and gzipped content, i.e. all comments. At any point, the user can restore such backup and revert all comments to the desired state.

Note: Restore procedure cleans the current data store and replaces all comments with comments from the backup file.

For safety and security reasons restore functionality not exposed outside of your server by default. The recommended way to restore from the backup is to use provided scripts/restore-backup.sh. It can run inside the container:

docker exec -it remark42 restore -f {backup-filename.gz} -s {your site ID}

Manual backup

In addition to automatic backups, user can make a backup manually. This command makes userbackup-{site ID}-{timestamp}.gz by default.

docker exec -it remark42 backup -s {your site ID}

Restore from backup

Restore will clean all comments first and then will process with complete import from a given file.

docker exec -it remark42 restore -f {backup file name} -s {your site ID}

Backup format

The backup file is a text file with all exported comments separated by EOL. Each backup record is a valid JSON with all key/value unmarshaled from Comment struct (see below).

Admin users

Admins/moderators should be defined in docker-compose.yml as a list of user IDs or passed in the command line.

  - ADMIN_SHARED_ID=github_ef0f706a79cc24b17bbbb374cd234a691a034128,github_dae9983158e9e5e127ef2b87a411ef13c891e9e5

To get a user ID just log in and click on your username or any other user you want to promote to admins. It will expand login info and show the full user ID.

Docker parameters

Two parameters allow customizing Docker container on the system level:

  • APP_UID - sets UID to run Remark42 application in container (default=1001)
  • TIME_ZONE - sets time zone of Remark42 container (default=America/Chicago)

see umputun/baseimage for more details

Example of docker-compose.yml:

version: '2'

    image: umputun/remark42:latest
    restart: always
    container_name: "remark42"
      - APP_UID=2000                          # runs Remark42 app with non-default UID
      - TIME_ZONE=GTC                         # sets container time to UTC
      - REMARK_URL=https://demo.remark42.com  # URL pointing to your Remark42 server
      - SITE=YOUR_SITE_ID                     # site ID, same as used for `site_id`, see "Setup on your website"
      - SECRET=abcd-123456-xyz-$%^&           # secret key
      - AUTH_GITHUB_CID=12345667890           # OAuth2 client ID
      - AUTH_GITHUB_CSEC=abcdefg12345678      # OAuth2 client secret
      - ./var:/srv/var                        # persistent volume to store all Remark42 data

Setup on your website


It's the main widget that renders a list of comments.

Add this snippet to the bottom of web page:

  var remark_config = {
    host: "REMARK_URL", // hostname of Remark42 server, same as REMARK_URL in backend config, e.g. "https://demo.remark42.com"
    site_id: 'YOUR_SITE_ID',
    components: ['embed'], // optional param; which components to load. default to ["embed"]
                           // to load all components define components as ['embed', 'last-comments', 'counter']
                           // available component are:
                           //   - 'embed': basic comments widget
                           //   - 'last-comments': last comments widget, see `Last Comments` section below
                           //   - 'counter': counter widget, see `Counter` section below
    url: 'PAGE_URL', // optional param; if it isn't defined
                     // `window.location.origin + window.location.pathname` will be used
                     // Note that if you use query parameters as significant part of URL
                     // (the one that actually changes content on page)
                     // you will have to configure URL manually to keep query params, as
                     // `window.location.origin + window.location.pathname` doesn't contain query params and
                     // hash. For example, default URL for `https://example/com/example-post?id=1#hash`
                     // would be `https://example/com/example-post`
                     // The problem with query params is that they often contain useless params added by
                     // various trackers (utm params) and doesn't have defined order, so Remark42 treats differently
                     // all this examples:
                     // https://example.com/?postid=1&date=2007-02-11
                     // https://example.com/?date=2007-02-11&postid=1
                     // https://example.com/?date=2007-02-11&postid=1&utm_source=google
                     // If you deal with query parameters make sure you pass only significant part of it
                     // in well defined order
    max_shown_comments: 10, // optional param; if it isn't defined default value (15) will be used
    theme: 'dark', // optional param; if it isn't defined default value ('light') will be used
    page_title: 'Moving to Remark42', // optional param; if it isn't defined `document.title` will be used
    locale: 'en', // set up locale and language, if it isn't defined default value ('en') will be used
    show_email_subscription: false, // optional param; by default it is `true` and you can see email subscription feature
                                    // in interface when enable it from backend side
                                    // if you set this param in `false` you will get notifications email notifications as admin
                                    // but your users won't have interface for subscription
    simple_view: false // optional param; overrides the parameter from the backend
                       // minimized UI with basic info only
<script>!function(e,n){for(var o=0;o<e.length;o++){var r=n.createElement("script"),c=".js",d=n.head||n.body;"noModule"in r?(r.type="module",c=".mjs"):r.async=!0,r.defer=!0,r.src=remark_config.host+"/web/"+e[o]+c,d.appendChild(r)}}(remark_config.components||["embed"],document);</script>

And then add this node in the place where you want to see Remark42 widget:

<div id="remark42"></div>

After that widget will be rendered inside this node.

If you want to set this up on a Single Page App, see [appropriate doc page](site/src/docs/configuration/frontend/index.md).


Right now Remark42 has two themes: light and dark. You can pick one using a configuration object, but there is also a possibility to switch between themes in runtime. For this purpose Remark42 adds to window object named REMARK42, which contains a function changeTheme. Just call this function and pass a name of the theme that you want to turn on:


Right now Remark42 is translated to English (en), Belarusian (be), Brazilian Portuguese (bp), Bulgarian (bg), Chinese (zh), Finnish (fi), French (fr), German (de), Japanese (ja), Korean (ko), Polish (pl), Russian (ru), Spanish (es), Turkish (tr), Ukrainian (ua) and Vietnamese (vi) languages. You can pick one using configuration object.

Do you want to translate Remark42 to other locales? Please see [this documentation](site/src/docs/contributing/translations/index.md) for details.

Last comments

It's a widget that renders the list of last comments from your site.

Add this snippet to the bottom of web page, or adjust already present remark_config to have last-comments in components list:

  var remark_config = {
    host: "REMARK_URL", // hostname of Remark42 server, same as REMARK_URL in backend config, e.g. "https://demo.remark42.com"
    site_id: 'YOUR_SITE_ID',
    components: ['last-comments']

And then add this node in the place where you want to see last comments widget:

<div class="remark42__last-comments" data-max="50"></div>

data-max sets the max amount of comments (default: 15).


It's a widget that renders several comments for the specified page.

Add this snippet to the bottom of web page, or adjust already present remark_config to have counter in components list:

  var remark_config = {
    host: "REMARK_URL", // hostname of Remark42 server, same as REMARK_URL in backend config, e.g. "https://demo.remark42.com"
    site_id: 'YOUR_SITE_ID',
    components: ['counter']

And then add a node like this in the place where you want to see a number of comments:

<span class="remark42__counter" data-url="https://domain.com/path/to/article/"></span>

You can use as many nodes like this as you need to. The script will found all of them by the class remark__counter, and it will use data-url attribute to define the page with comments.

Also script can use url property from remark_config object, or window.location.origin + window.location.pathname if nothing else is defined.

Build from the source

  • to build Docker container - make docker. This command will produce container umputun/remark42
  • to build a single binary for direct execution - make OS=<linux|windows|darwin> ARCH=<amd64|386>. This step will produce executable remark42 file with everything embedded


You can use a fully functional local version to develop and test both frontend and backend. It requires at least 2GB RAM or swap enabled.

To bring it up run:

# if you mainly work on backend
cp compose-dev-backend.yml compose-private.yml
# if you mainly work on frontend
cp compose-dev-frontend.yml compose-private.yml
# now, edit / debug `compose-private.yml` to your heart's content

# build and run
docker-compose -f compose-private.yml build
docker-compose -f compose-private.yml up

It starts Remark42 on and adds local OAuth2 provider "Dev". To access the UI demo page go to By default, you would be logged in as dev_user which is defined as admin. You can tweak any of supported parameters in corresponded yml file.

Backend Docker Compose config by default skips running frontend related tests. Frontend Docker Compose config by default skips running backend related tests and sets NODE_ENV=development for frontend build.

Backend development

To run backend locally (development mode, without Docker) you have to have the latest stable go toolchain installed.

To run backend - cd backend; go run app/main.go server --dbg --secret=12345 --url= --admin-passwd=password --site=remark. It stars backend service with embedded bolt store on port 8080 with basic auth, allowing to authenticate and run requests directly, like this:

HTTP http://admin:[email protected]:8080/api/v1/find?site=remark&sort=-active&format=tree&url=

Frontend development

Developer guide

Frontend guide can be found here: [./frontend/README.md](./frontend/README.md).


You should have at least 2GB RAM or swap enabled for building.

  • install Node.js 12.11 or higher
  • install NPM 6.13.4
  • run npm install inside ./frontend
  • run npm run build there
  • result files will be saved in ./frontend/public

Note: Running npm install will set up pre-commit hooks into your git repository. It used to reformat your frontend code using prettier and lint with eslint and stylelint before every commit.


For local development mode with Hot Reloading use npm start instead of npm run build. In this case, webpack will serve files using webpack-dev-server on localhost:9000. By visiting you will get a page with the main comments widget communicating with a demo server backend running on https://demo.remark42.com. But you will not be able to log in with any OAuth providers due to security reasons.

You can attach to the locally running backend by providing REMARK_URL environment variable.

npx cross-env REMARK_URL= npm start

Note: If you want to redefine env variables such as PORT on your local instance you can add .env file to ./frontend folder and rewrite variables as you wish. For such functional, we use dotenv.

The best way to start a local developer environment:

cp compose-dev-frontend.yml compose-private-frontend.yml
docker-compose -f compose-private-frontend.yml up --build
cd frontend
npm run dev

Developer build running by webpack-dev-server supports devtools for React and Redux.



  • GET /auth/{provider}/login?from=http://url&site=site_id&session=1 - perform "social" login with one of supported providers and redirect to url. Presence of session (any non-zero value) change the default cookie expiration and makes them session-only
  • GET /auth/logout - logout
type User struct {
    Name     string `json:"name"`
    ID       string `json:"id"`
    Picture  string `json:"picture"`
    Admin    bool   `json:"admin"`
    Blocked  bool   `json:"block"`
    Verified bool   `json:"verified"`


  • POST /api/v1/comment - add a comment, auth required
type Comment struct {
    ID          string    `json:"id"`      // comment ID, read only
    ParentID    string    `json:"pid"`     // parent ID
    Text        string    `json:"text"`    // comment text, after md processing
    Orig        string    `json:"orig"`    // original comment text
    User        User      `json:"user"`    // user info, read only
    Locator     Locator   `json:"locator"` // post locator
    Score       int       `json:"score"`   // comment score, read only
    Vote        int       `json:"vote"`    // vote for the current user, -1/1/0
    Controversy float64   `json:"controversy,omitempty"` // comment controversy, read only
    Timestamp   time.Time `json:"time"`    // time stamp, read only
    Edit        *Edit     `json:"edit,omitempty" bson:"edit,omitempty"` // pointer to have empty default in JSON response
    Pin         bool      `json:"pin"`     // pinned status, read only
    Delete      bool      `json:"delete"`  // delete status, read only
    PostTitle   string    `json:"title"`   // post title

type Locator struct {
    SiteID string `json:"site"` // site ID
    URL    string `json:"url"`  // post URL

type Edit struct {
    Timestamp time.Time `json:"time" bson:"time"`
    Summary   string    `json:"summary"`
  • POST /api/v1/preview - preview comment in HTML. Body is Comment to render
  • GET /api/v1/find?site=site-id&url=post-url&sort=fld&format=tree|plain - find all comments for given post

This is the primary call used by UI to show comments for the given post. It can return comments in two formats - plain and tree. In plain format result will be sorted list of Comment. In tree format this is going to be tree-like object with this structure:

type Tree struct {
    Nodes []Node         `json:"comments"`
    Info  store.PostInfo `json:"info,omitempty"`

type Node struct {
    Comment store.Comment `json:"comment"`
    Replies []Node        `json:"replies,omitempty"`

Sort can be time, active or score. Supported sort order with prefix -/+, i.e. -time. For tree mode sort will be applied to top-level comments only and all replies are always sorted by time.

  • PUT /api/v1/comment/{id}?site=site-id&url=post-url - edit comment, allowed once in EDIT_TIME minutes since creation. Body is EditRequest JSON
type EditRequest struct {
    Text    string `json:"text"`    // updated text
    Summary string `json:"summary"` // optional, summary of the edit
    Delete  bool   `json:"delete"`  // delete flag
  • GET /api/v1/last/{max}?site=site-id&since=ts-msec - get up to {max} last comments, since (epoch time, milliseconds) is optional
  • GET /api/v1/id/{id}?site=site-id - get comment by comment id
  • GET /api/v1/comments?site=site-id&user=id&limit=N - get comment by user id, returns response object
type response struct {
    Comments []store.Comment `json:"comments"`
    Count    int             `json:"count"`
  • GET /api/v1/count?site=site-id&url=post-url - get comment's count for {url}
  • POST /api/v1/count?site=siteID - get number of comments for posts from post body (list of post IDs)
  • GET /api/v1/list?site=site-id&limit=5&skip=2 - list commented posts, returns array or PostInfo, limit=0 will return all posts
type PostInfo struct {
    URL      string    `json:"url"`
    Count    int       `json:"count"`
    ReadOnly bool      `json:"read_only,omitempty"`
    FirstTS  time.Time `json:"first_time,omitempty"`
    LastTS   time.Time `json:"last_time,omitempty"`
  • GET /api/v1/user - get user info, auth required
  • PUT /api/v1/vote/{id}?site=site-id&url=post-url&vote=1 - vote for comment. vote=1 will increase score, -1 decrease, auth required
  • GET /api/v1/userdata?site=site-id - export all user data to gz stream, auth required
  • POST /api/v1/deleteme?site=site-id - request deletion of user data, auth required
  • GET /api/v1/config?site=site-id - returns configuration (parameters) for given site
type Config struct {
    Version        string   `json:"version"`
    EditDuration   int      `json:"edit_duration"`
    MaxCommentSize int      `json:"max_comment_size"`
    Admins         []string `json:"admins"`
    AdminEmail     string   `json:"admin_email"`
    Auth           []string `json:"auth_providers"`
    LowScore       int      `json:"low_score"`
    CriticalScore  int      `json:"critical_score"`
    PositiveScore  bool     `json:"positive_score"`
    ReadOnlyAge    int      `json:"readonly_age"`
    MaxImageSize   int      `json:"max_image_size"`
    EmojiEnabled   bool     `json:"emoji_enabled"`
  • GET /api/v1/info?site=site-idd&url=post-url - returns PostInfo for site and URL

Streaming API

Streaming API provides server-sent events for post updates as well as a site update:

  • GET /api/v1/stream/info?site=site-idd&url=post-url&since=unix_ts_msec - returns stream (event: info) with PostInfo records for the site and URL. since is optional
  • GET /api/v1/stream/last?site=site-id&since=unix_ts_msec - returns updates stream (event: last) with comments for the site, since is optional

Response example

data: {"url":"https://radio-t.com/blah1","count":2,"first_time":"2019-06-18T12:53:48.125686-05:00","last_time":"2019-06-18T12:53:48.142872-05:00"}

event: info
data: {"url":"https://radio-t.com/blah1","count":3,"first_time":"2019-06-18T12:53:48.125686-05:00","last_time":"2019-06-18T12:53:48.157709-05:00"}

event: info
data: {"url":"https://radio-t.com/blah1","count":4,"first_time":"2019-06-18T12:53:48.125686-05:00","last_time":"2019-06-18T12:53:48.172991-05:00"}

event: info
data: {"url":"https://radio-t.com/blah1","count":5,"first_time":"2019-06-18T12:53:48.125686-05:00","last_time":"2019-06-18T12:53:48.188429-05:00"}

event: info
data: {"url":"https://radio-t.com/blah1","count":6,"first_time":"2019-06-18T12:53:48.125686-05:00","last_time":"2019-06-18T12:53:48.204742-05:00"}

event: info
data: {"url":"https://radio-t.com/blah1","count":7,"first_time":"2019-06-18T12:53:48.125686-05:00","last_time":"2019-06-18T12:53:48.220692-05:00"}

event: info
data: {"url":"https://radio-t.com/blah1","count":8,"first_time":"2019-06-18T12:53:48.125686-05:00","last_time":"2019-06-18T12:53:48.23817-05:00"}

event: info
data: {"url":"https://radio-t.com/blah1","count":9,"first_time":"2019-06-18T12:53:48.125686-05:00","last_time":"2019-06-18T12:53:48.254669-05:00"}

RSS feeds

  • GET /api/v1/rss/post?site=site-id&url=post-url - RSS feed for a post
  • GET /api/v1/rss/site?site=site-id - RSS feed for given site
  • GET /api/v1/rss/reply?site=site-id&user=user-id - RSS feed for replies to user's comments

Images management

  • GET /api/v1/picture/{user}/{id} - load stored image
  • POST /api/v1/picture - upload and store image, uses post form with FormFile("file"). Returns {"id": user/imgid}, auth required

returned ID should be appended to load image URL on caller side

Email subscription

  • GET /api/v1/email?site=site-id - get user's email, auth required
  • POST /api/v1/email/subscribe?site=site-id&[email protected] - makes confirmation token and sends it to user over email, auth required

Trying to subscribe to the same email a second time will return response code 409 Conflict and explaining error message

  • POST /api/v1/email/confirm?site=site-id&tkn=token - uses provided token parameter to set email for the user, auth required

Setting email subscribe user for all first-level replies to his messages

  • DELETE /api/v1/email?site=siteID - removes user's email, auth required


  • DELETE /api/v1/admin/comment/{id}?site=site-id&url=post-url - delete comment by id
  • PUT /api/v1/admin/user/{userid}?site=site-id&block=1&ttl=7d - block or unblock user with optional TTL (default=permanent)
  • GET api/v1/admin/blocked&site=site-id - list of blocked user IDs
type BlockedUser struct {
    ID    string    `json:"id"`
    Name  string    `json:"name"`
    Until time.Time `json:"time"`
  • GET /api/v1/admin/export?site=site-id&mode=[stream|file] - export all comments to JSON stream or gz file
  • POST /api/v1/admin/import?site=site-id - import comments from the backup, uses post body
  • POST /api/v1/admin/import/form?site=site-id - import comments from the backup, user post form
  • POST /api/v1/admin/remap?site=site-id - remap comments to different URLs. Expect list of "from-url new-url" pairs separated by \n. From-url and new-url parts are separated by space. If URLs end with an asterisk (*) it means matching by the prefix. Remap procedure based on export/import chain so make the backup first
http://oldsite.com* https://newsite.com*
http://oldsite.com/from-old-page/1 https://newsite.com/to-new-page/1
  • GET /api/v1/admin/wait?site=site-id - wait for completion for any async migration ops (import or remap)
  • PUT /api/v1/admin/pin/{id}?site=site-id&url=post-url&pin=1 - pin or unpin comment
  • GET /api/v1/admin/user/{userid}?site=site-id - get user's info
  • DELETE /api/v1/admin/user/{userid}?site=site-id - delete all user's comments
  • PUT /api/v1/admin/readonly?site=site-id&url=post-url&ro=1 - set read-only status
  • PUT /api/v1/admin/verify/{userid}?site=site-id&verified=1 - set verified status
  • GET /api/v1/admin/deleteme?token=token - process deleteme user's request

all admin calls require auth and admin privilege


  • Remark42 is trying to be very sensitive to any private or semi-private information.
  • Authentication requesting the minimal possible scope from authentication providers. All extra information returned by them is immediately dropped and not stored in any form.
  • Generally, Remark42 keeps user ID, username and avatar link only. None of these fields exposed directly - ID and name hashed, avatar proxied.
  • There is no tracking of any sort.
  • Login mechanic uses JWT stored in a cookie (HttpOnly, secured). The second cookie (XSRF_TOKEN) is a random ID preventing CSRF.
  • There is no cross-site login, i.e. user's behavior can't be analyzed across independent sites running Remark42.
  • There are no third-party analytic services involved.
  • User can request all information Remark42 knows about and export to gz file.
  • Supported complete cleanup of all information related to user's activity.
  • Cookie lifespan can be restricted to session-only.
  • All potentially sensitive data stored by Remark42 hashed and encrypted.

Technical details

  • Data stored in boltdb (embedded key/value database) files under STORE_BOLT_PATH.
  • Each site is stored in a separate boltdb file.
  • To migrate/move Remark42 to another host boltdb files as well as avatars directory AVATAR_FS_PATH should be transferred. Optionally, boltdb can be used to store avatars as well.
  • Automatic backup process runs every 24h and exports all content in JSON-like format to backup-remark-YYYYMMDD.gz.
  • Authentication implemented with go-pkgz/auth stored in a cookie. It uses HttpOnly, secure cookies.
  • All heavy REST calls cached internally in LRU cache limited by CACHE_MAX_ITEMS and CACHE_MAX_SIZE with go-pkgz/rest.
  • User's activity throttled globally (up to 1000 simultaneous requests) and limited locally (per user, usually up to 10 req/sec).
  • Request timeout set to 60sec.
  • Admin authentication (--admin-password set) allows to hit Remark42 API without social login and with admin privileges. Adds basic-auth for username: admin, password: ${ADMIN_PASSWD}.
  • User can vote for the comment multiple times but only to change the vote. Double voting is not allowed.
  • User can edit comments in 5 mins (configurable) window after creation.
  • User ID hashed and prefixed by OAuth provider name to avoid collisions and potential abuse.
  • All avatars resized and cached locally to prevent rate limiters from OAuth providers, part of go-pkgz/auth functionality.
  • Images served over HTTP can be proxied to HTTPS (IMAGE_PROXY_HTTP2HTTPS=true) to prevent mixed HTTP/HTTPS.
  • All images can be proxied and saved locally (IMAGE_PROXY_CACHE_EXTERNAL=true) instead of serving from the original location. Beware, images that are posted with this parameter enabled will be served from proxy even after it will be disabled.
  • Docker build uses publicly available base images.

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