Deploy Remark42

Deploy and Host Remark42 on Railway

Remark42 is an open-source commenting engine, written in Go by Umputun, that you embed on any web page with a single script tag. It gives readers threaded discussions, markdown, voting and email or OAuth sign-in, and it gives you what hosted comment platforms never do: the comments themselves, in a file you own, with no third-party tracking scripts. Bloggers, documentation sites and static-site builders on Hugo, Astro or Next.js all end up here.

Self-host Remark42 on Railway and this template wires up the parts that usually take an afternoon. The remark42 service runs umputun/remark42:latest behind a public HTTPS domain, keeping every comment, avatar, uploaded image and nightly backup on a volume at /srv/var. A second service, mailpit, provides SMTP on the private network so email sign-in links and notifications work the moment the deploy finishes, with a password-protected inbox for reading what was sent. Run Remark42 on Railway and the public URL, the signing secret, the trusted-proxy ranges and the mail wiring are already set.

Getting Started with Remark42 on Railway

Open the remark42 service's public URL and add /web/ — that path serves a demo page with the widget pointed at your own instance, and it is the fastest way to confirm the deployment works. There is no admin account and no default password: click Sign In, choose Email, enter any username and address, and Remark42 mails a one-time token. Open the mailpit URL, sign in with the credentials in its MP_UI_AUTH variable, copy the token out of the message and paste it into the widget.

Now make yourself a moderator. Click your own name in the widget to expand your profile and copy the user id, which looks like email_91dbc8cf…. Put it in the remark42 service's ADMIN_SHARED_ID variable — a comma-separated list — and let the service redeploy. Reload, and every comment gains a moderation menu: pin, hide, verify the author, block, delete. Post a test comment, reply to it, and check Mailpit again: a New comment to your site message should be waiting. Then copy the embed snippet from /web/ into your own site.

About Hosting Remark42

Remark42 replaces a hosted comment service with one Go binary and an embedded BoltDB database. No database server, no queue, no cache tier — the installation is one process and one directory. A five-year-old instance with regular activity fits in under 200 MB, and the backup is a gzipped JSON dump the server writes itself every 24 hours.

Key features:

• Threaded comments with full markdown, code blocks, image uploads and emoji
• Sign-in by email token, anonymous name, or OAuth with GitHub, Google, Microsoft, Apple, Facebook, Yandex, Discord, Patreon or a custom provider
• Voting with score thresholds that hide low-scored comments automatically
• Moderation: pin, hide, verify, delete, block, restricted word and name lists
• Email and Telegram notifications, RSS feeds per thread
• Multi-site support from one instance, and an import path from Disqus and WordPress

The remark42 service is the whole application — API, widget assets and storage. mailpit exists because Remark42's most convenient sign-in method is an emailed token, and a fresh deployment with no SMTP host could not send one. Mailpit captures mail rather than delivering it, so it is a safe place to watch notifications before you point Remark42 at a real relay.

Why Deploy Remark42 on Railway

Railway removes the server work from a self-hosted comment engine:

• One click provisions both services, both volumes and the public HTTPS domain
• The signing secret is generated at deploy time
• TRUSTED_PROXY is pre-set to Railway's edge, so per-IP rate limiting works
• Volumes keep comments across every redeploy
• Health checks on /ping and /livez catch a bad rollout

Common Use Cases

• Comments on a static blog built with Hugo, Astro, Eleventy or Next.js, with no third-party tracking script
• Replacing Disqus on an existing site, importing the old threads from a Disqus export
• One instance across several domains, with SITE separating each site's comments
• Feedback on internal docs, sign-in restricted to your company's OAuth provider

Remark42 vs Other Comment Engines

Remark42 sits between Giscus, which needs every commenter to hold a GitHub account, and Commento, which needs a PostgreSQL server of its own.

Dependencies for Remark42

• umputun/remark42:latest — the comment engine; API, widget and BoltDB storage in one binary
• axllent/mailpit:latest — SMTP server and inbox holding the sign-in tokens and notifications

Environment Variables Reference

Deployment Dependencies

• Source: github.com/umputun/remark42 (MIT), docs
• Images: umputun/remark42, axllent/mailpit

Hardware Requirements for Self-Hosting Remark42

Upstream reports busy instances idling under 0.1% CPU and around 80 MB of RAM. The volume grows slowly; most of it is images, not comment text.

Self-Hosting Remark42 with Docker

The minimum is two variables and a mounted directory:

docker run -d --name remark42 \
  -p 8080:8080 \
  -e REMARK_URL=https://comments.example.com \
  -e SECRET=change-me-to-a-long-random-string \
  -e AUTH_ANON=true \
  -v $PWD/var:/srv/var \
  umputun/remark42:latest

The container refuses to start if /srv/var is not mounted — deliberately, since that is where your comments live. Embedding is a snippet plus a target element:

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

How Much Does Remark42 Cost to Self-Host?

Remark42 is MIT-licensed and free — no paid tier, no seat limits, no feature gating. The only cost is infrastructure, which on Railway means usage-based pricing for two small containers and two volumes. Disqus removes ads only on a paid plan, and Hyvor Talk charges per page view.

FAQ

What is Remark42? Remark42 is a self-hosted, open-source commenting engine written in Go. You embed it on any web page with a script tag, and it stores comments in a BoltDB file you own rather than in a vendor's cloud.

What does this Railway template deploy? Two services: remark42, the comment engine on a public HTTPS domain with a volume at /srv/var, and mailpit, a private SMTP server with a password-protected inbox that receives the sign-in tokens and notification emails.

Why does the template include a mail service? Remark42's email sign-in mails a one-time token, and its notifications are email too. Without an SMTP host neither works, so a deployment with no mail service has no usable login unless you enable anonymous commenting. Point SMTP_HOST and SMTP_PORT at a real relay when you go live.

How do I make myself an admin in self-hosted Remark42? There is no admin account. Sign in once, click your username in the widget to reveal your user id, and add it to ADMIN_SHARED_ID on the remark42 service. Moderation controls appear on the next load.

Can I use GitHub or Google sign-in instead of email? Yes. Register an OAuth application, point its callback at https://your-domain/auth/github/callback, and set AUTH_GITHUB_CID and AUTH_GITHUB_CSEC. Several providers can be enabled at once.

Will my comments survive a redeploy? Yes. Everything lives on the volume at /srv/var — the BoltDB file, avatars, uploads and the daily backup — and Railway keeps that volume across deployments.

Can one instance serve several websites? Yes. Set SITE to a comma-separated list of ids and give each page's remark_config.site_id the matching value. Each site gets its own database file and threads.