Key Features
A complete commenting system with live conversations, SSO, spam protection, and deep customization. With frontend and backend SDKs, integrate commenting and chat into any site or application.
Live Conversations
Your community chats in real time on your website or application.
Scalable
Millions of pages or thousands of comments per page? It won't slow us down.
SSO, Web hooks, Oh My
Bring your own login with secure SSO, and react to every comment event with signed webhooks.
Efficient Moderation
Moderate Quickly with Bulk Actions and Moderation Groups. Invite your moderators and get them to work.
Migrate in Minutes
Automated Migration from WordPress, Disqus, Commento, Muut Comments, IntenseDeba te, JustComments
Fight Spam
Get protected by a classifier that is continuously trained. Automatically remove unverified comments.
Notifications
Get fine grained, high level, scheduled, or immediate notifications.
Code & Markdown Support
Automatically detect, color, and format pasted code snippets.
Adaptive
Adapts to your site - whether it has a light or a dark theme.
Localized
The client-side widgets and emails are fully localized in 14+ languages using browser locale detection.
Custom Email Templates
Emails sent to users can be customized and styled.
Go Incognito
Allow anonymous commenting, where an email is not required to comment.
Increase Engagement
FastComments decreases the time to comment, either with SSO integration or by providing a low-friction way to sign up.
@Mentions
Tag users with our easy to use @mentions and they'll get notified right away.
#Hashtags
Autocompleted hashtags, with the ability to pre-seed hashtags that point to external content.
GIFs
GIF picker with anonymized integrations with major providers.
Subscriptions
Your users stay up to date about new activity via subscriptions.
JavaScript Not Required
Fully server-rendered solutions available.
Awards and Badges
Craft custom badges and reward your community.
User Profiles
User Profiles complete with activity feeds and guestbook.
Direct Messaging
Realtime messaging between users of your community.
Ratings, Reactions, Surveys
Collect and report on reviews, reacts, and surveys.
Access Control
Group users and limit access to comments.
Notifications
We help your community keep in touch with each other via reply, thread, and reaction notifications.
Analytics
Built in analytics tools to monitor your site's traffic and activity at no extra cost.
Full Text Search
Moderators can search for comments by their text, or add search to any comment widget directly.
AI Agents
Configure AI Agents to summarize threads, send welcome emails, moderate comments, and more.
Comments appear the moment they are posted. FastComments keeps every reader on the same page over secure WebSockets, with no refresh and no polling.
- New comments, edits, votes, and pins reach every open tab and device instantly.
- New replies wait behind a "Show New Comments" button so the page never jumps, or stream in chat-style for live events and auctions.
- Each update is under 1KB on the wire, and dropped connections reconnect and resync on their own.
- Go beyond the comment box: readers can discuss highlighted text or drop chat markers directly on images.
FastComments is engineered for low P99 latency on hardware most platforms would call a rounding error. We publish our sizing numbers because we are proud of them.
- A single CPU core serves around 100 comment threads per second in under 250MB of memory.
- Pagination is precomputed for every sort order, so page 500 loads as fast as page 1 on threads with thousands of comments.
- Our published sizing tables cover 100 to 1,000,000 concurrent users.
- Widgets and assets ship from a global CDN, and bulk tools handle millions of comments in a few clicks.
Plug FastComments into your existing user base and event pipeline. Sign users in with your own auth, and get notified the instant anything changes.
- Secure SSO is one HMAC-SHA256 hash built server-side. No new endpoints, no libraries, with examples in Node, Java, and PHP.
- SAML 2.0 support works with Okta, Azure AD, and Active Directory.
- Webhooks fire on comment create, update, and remove, signed with HMAC and retried automatically by a queue you can watch from the admin.
- Existing comments migrate to your users' accounts automatically the first time they sign in.
Clear a queue of thousands before your coffee cools. Moderation is keyboard-driven, real-time, and built for teams.
- Bulk actions select every matching comment server-side, across millions, with pause, resume, and Ctrl+Z undo.
- Vim-style shortcuts: j and k to move, a to approve, s for spam, b to ban.
- Moderation Groups route each moderator to just their section of the community.
- Approve, mark spam, or review straight from the email digest with one-click magic links.
Switching comment systems should not be a project. Upload your export and watch it run. Most migrations finish in a couple of minutes.
- Automated imports from Disqus, WordPress, Commento, Hyvor Talk, Muut, IntenseDebate, Just-Comments, and AnyComment.
- Comments, replies, users, and avatars come across. Re-running an import never creates duplicates, so you can do a test pass first.
- Import files are locked from outside access and deleted the moment the import completes.
- Leaving is just as easy: exports and WordPress sync-back mean your data stays yours.
Spam gets cheaper to send every year. FastComments answers with classifiers that learn from every moderation decision you make.
- Pick a network-wide classifier, a private model trained only on your site, or LLM-based detection.
- A per-user Trust Factor relaxes filtering for proven community members and tightens it for strangers.
- Wildcard bans for whole email domains, plus-alias detection, shadow bans, and hashed IP bans.
- Auto-approve only email-verified comments and let unverified ones expire on a timer.
Bring readers back without burying them. Replies, mentions, and subscribed pages notify by email and the in-widget bell, on the schedule each user picks.
- Reply and mention emails send within a minute; page subscriptions can digest hourly or daily, per subscription.
- Empty digests are never sent, and one verification email per session keeps inboxes calm.
- Bounced and complained addresses are suppressed automatically every day.
- Every email carries one-click unsubscribe headers, and SSO sites can use their own unsubscribe links.
Paste a snippet and FastComments detects it, formats it, and highlights it, no markup required.
- Automatic language detection with syntax highlighting for 39 languages, from Bash to TypeScript.
- Markdown for bold, italics, quotes, lists, and code fences, plus a formatting toolbar.
- Every comment runs through DOMPurify and sanitize-html; scripts, styles, and event handlers never survive.
- Optional media embeds from trusted providers like YouTube, Vimeo, SoundCloud, and Spotify.
Your comments should look native to your site, not bolted on. FastComments measures the background it sits on and themes itself to match.
- Dark mode triggers on actual background luminance, not just the OS setting, and swaps icons along with colors.
- The system font stack is the default, so the widget feels native on every device.
- Full custom CSS support, a no-styles mode for total control, and live theme switching without a reload.
- Your custom CSS is tested against every FastComments release before it ships.
Your readers see FastComments in their language before they type a word. Widgets, emails, and notifications localize automatically from the browser locale.
- 27 locales and counting, including regional variants like Brazilian Portuguese, Traditional Chinese, and four flavors of Serbian.
- Every string is overridable, from one button label to the entire widget.
- Emails render in the last locale each user actually used.
- Restrict your community to specific languages, enforced by automatic detection of each comment.
Every email FastComments sends can look like it came from you, because it did. Your domain, your logo, your markup.
- Full EJS templating with variables and conditional logic, not just token swaps.
- Send from your own domain with SPF and DKIM, configured per site.
- Live preview with editable test data; a template that fails to render cannot be saved.
- Production render errors are counted per template, so silent failures are not silent.
Some communities work better when nobody has to hand over an email. Turn on anonymous commenting and the email field becomes optional, or remove it entirely.
- Comments post instantly; verification is never a wall in front of the conversation.
- Cookieless verification sessions send at most one email per visit.
- Anonymous voting is a separate toggle, so you can allow reactions without signups.
- Auto-expire unverified comments after a set number of days to keep spam from piling up.
Every extra field between a reader and the comment button costs you comments. FastComments strips the signup ceremony down to almost nothing.
- Leave an email while commenting and an account is created automatically. No password, ever: login links sign users in from their inbox.
- Notification emails double as magic links that drop users straight back into the conversation.
- With SSO, your logged-in users comment with zero additional steps.
- Comment counts, recent-discussion widgets, and feeds pull readers deeper into your site.
Type @ and start a name. The right person gets an email, and the conversation keeps moving.
- Autocomplete draws from commenters on the page, your site's accounts, moderators, and your SSO user directory.
- Pre-load your entire user base into autocomplete through the API.
- Scope who can be tagged with mention groups, so private cohorts stay private.
- Full keyboard navigation, and stray @ signs are detected and left alone.
Hashtags in FastComments are a navigation layer, not decoration. Every tag is a link, and you decide where it goes.
- Autocomplete as users type, drawing community-created and API-defined tags from one dataset.
- Point any tag at external content: a product page, a ticket, a video.
- Clicking a tag pulls up every comment across your site that shares it.
- Lock the taxonomy by disabling automatic tag creation, and bulk-load tags through the API.
Reaction GIFs, minus the tracking. The built-in picker proxies every request, so the GIF provider never sees your users.
- Trending GIFs plus search, right in the comment area.
- All provider calls are anonymized: no cookies, no IP addresses shared.
- Content rating is configurable from G to R, with image moderation levels on top.
- Users can also upload .gif and .webp files up to 20MB.
Readers who subscribe come back on their own. One click on the bell follows a page, and new activity lands in their inbox on their schedule.
- Per-subscription delivery: instant, hourly digest, or daily digest.
- If nothing happened, no email goes out.
- A full subscription API lets users follow anything with an ID, not just web pages.
- Optional RSS feeds with secure URLs you can rotate at any time.
The comment widget renders as plain HTML on the server. Readers can view, post, reply, and vote with JavaScript disabled.
- Server-side rendering supports SSO, nested replies, pagination, sorting, and even anonymous voting.
- It is the same rendering engine as the JS widget, so your custom styling applies unchanged.
- The WordPress plugin ships the no-JS fallback by default, and our own blog runs on it.
- Render comments yourself with SDKs for PHP, Python, Ruby, Go, Java, Rust, Swift, Dart, C++, and Nim.
Badges give your regulars a reason to stay regulars. Define the milestones and FastComments awards them automatically, even retroactively.
- Thresholds on comments, upvotes, replies, pins, and tenure, plus fun ones like Night Owl and a 40-second Fast Reply badge.
- Image badges, animated GIFs included, or styled text shown on comments and profiles.
- Stack badges, or have new ranks replace old ones as members level up.
- New badge rules re-scan your entire history, so long-time members get credit for what they already did.
Every commenter gets a real profile: avatar, banner, bio, badges, karma, and an activity feed. It is a social layer that comes with your comments.
- Activity and reputation follow users across every FastComments-powered site.
- Profile guestbooks with four approval modes, from wide open to fully moderated.
- Live presence indicators and real-time updates over WebSockets.
- Users control their own privacy: private activity, private guestbooks, messaging off.
Let members take it to DMs without leaving your site. Private one-on-one messaging is built in, in real time.
- Messages deliver instantly over WebSockets, with online presence and unread counters.
- Conversation history persists indefinitely across sessions and devices.
- Start a conversation from any comment or any profile.
- Users can turn messaging off or block someone entirely; admins can disable it globally.
Ratings, Reactions, Surveys
One feedback engine, three jobs. The same configurable questions power product reviews, page reactions, and quick surveys.
- Star, NPS, slider, and thumbs question types, with sub-ratings for detail.
- Answering reveals a live breakdown: averages, distributions, and counts for the page.
- An embeddable summary widget and a feedback analytics dashboard, included in every plan.
- Configure different questions per page or per site without touching code.
Not every conversation is for everyone. Group your users and pages, and FastComments enforces who sees what, down to the mention.
- User-level groups host separate conversations on the same page, invisible to each other.
- Page-level groups gate whole sections, built for memberships and paywalls.
- @mentions respect group boundaries; outsiders cannot even be tagged.
- Require SSO to read comments at all, on the domains or pages you choose.
Conversations only grow when people hear back. Reply, thread, and reaction notifications reach your community through email and the in-widget bell.
- The bell shows unread replies, upvotes, and subscribed-page activity at a glance.
- Users pick their own cadence, from instant to a daily digest, per subscription.
- Anti-fatigue by design: batching, empty-digest suppression, and per-thread opt-outs.
- SSO users carry their notification preferences in your own payload.
Know what your community is doing right now, not last week. Analytics is built in, exact, and free with every plan.
- A live view of users online and which pages they are on, with zero delay.
- Page loads, comments, votes, and new accounts tracked daily, never sampled.
- When counts can be imperfect they err low. We never inflate your numbers.
- See your projected next invoice before it bills, and forward events to Google Analytics.
Find that one comment from eight months ago. Moderators get search operators; readers can get a search box right in the widget.
- Operators like user:, page:, site:, and exact= narrow millions of comments instantly.
- Fuzzy matching, exact phrases, and hashtag search across your whole account.
- One setting adds search to any comment widget, no code required.
- The same search is exposed through the API and SDKs for 10+ languages.
AI Agents keep watch while you sleep and act with the exact permissions you grant, nothing more.
- 15 triggers, from first-time commenters to flag thresholds, with tools like approve, pin, warn, badge, and summarize.
- Every new agent starts in Dry-Run: it decides, records, and touches nothing until you are ready.
- Per-tool approval gates, hard budget caps, and a justification with confidence score on every action.
- Agents run after comments post, so readers never wait on a model.
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