Liveblocks vs Siren
An independent, review-free comparison compiled by the SaaSTracker editorial team. Both products are profiled in full, and neither can pay for placement here.
Still shortlisting? Browse the best in Notification Infrastructure for every option we track, with award winners called out.
The short answer
Both sides assessedLiveblocks compared with Siren
Opposite answers to who the notification is about. Siren routes across nine channels including WhatsApp, Discord, and LINE, adds provider pools and an agent toolkit, has no free tier, and starts at $249 a month. Liveblocks stops at in-app, email, Slack, Microsoft Teams, and web push, is free for 200 custom notifications a month, and generates the rest from comments and mentions at no cost. If an agent or a backend service is the sender and the channel mix is wide, Siren. If a colleague is the sender and the surface is a document, Liveblocks, for about a tenth of the money.
Siren compared with Liveblocks
Both put an inbox in your product and both stop short of sending email themselves, but the resemblance ends there. Liveblocks generates notifications out of collaboration: comments, mentions, and document activity, with batching, per-user channel settings, and a free plan, from $30 a month once you outgrow it. Siren generates them out of workflows and agent calls across nine channels, with no free tier and no batching. If your notifications are mostly about who commented on what, Liveblocks is both cheaper and closer to the problem. If they are about orders, alerts, approvals, and agent decisions crossing WhatsApp and Slack, Liveblocks does not compete.
Choose Liveblocks if
Product teams adding comments, mentions, or multiplayer editing to a web application who need the notification tray, the read state, the per-user channel settings, and the email digest hook that come with that work, and who are building in React.
Choose Siren if
Product and platform teams shipping multi-channel notifications where an AI agent is one of the senders, where the audience lives on WhatsApp, LINE, or Discord as well as email, or where the in-app inbox has to render in Vue, Flutter, or native Android rather than React.
Side by side
17 attributes| Attribute | Liveblocks | Siren |
|---|---|---|
| Category | Notifications | Notifications |
| Starting price | $0 (Free), then $30 per month (Pro), or $25 per month billed annually | $249 per month, or $208 per month billed annually (7 days trial) |
| Pricing model | A credit balance per month shared across every meter (collaboration minutes, comments, custom notifications, and realtime storage), with a free plan, two published paid tiers, and pay-as-you-go rates once the credits are spent. | A single published subscription priced on notification volume, with hard caps on stored users, campaigns, team members, and log retention, sold above a seven-day full-feature trial. No permanent free tier. |
| Free plan | Free includes 200 custom notifications a month, unlimited collaboration notifications, all six notification channels, notification settings, batching, pre-built components, 3,000 collaboration minutes, 200 comments, 3M realtime storage updates, 1 GB of realtime storage, 3 dashboard seats, and 10 simultaneous connections per room. | No |
| Free trial | No time-limited trial; the Free plan is permanent | 7 days with everything unlocked, no credit card required |
| Best for | Product teams adding comments, mentions, or multiplayer editing to a web application who need the notification tray, the read state, the per-user channel settings, and the email digest hook that come with that work, and who are building in React. | Product and platform teams shipping multi-channel notifications where an AI agent is one of the senders, where the audience lives on WhatsApp, LINE, or Discord as well as email, or where the in-app inbox has to render in Vue, Flutter, or native Android rather than React. |
| Setup time | A day to a working inbox if you are already using Comments, since the notifications generate themselves and the tray is a component. Two to four weeks for a full build that adds collaborative editing, custom notification kinds, and an email digest service you write yourself. | An afternoon to a first notification using QuickSend, and a few days to a published multi-channel workflow with templates and a provider configured. The MCP server and agent toolkit shorten the first integration considerably when the trigger is an agent rather than a service. |
| Learning curve | Moderate. Rooms, projects, threads, inbox notifications, and notification settings are clean concepts, but the split between what Liveblocks stores and what your backend still owns takes a little while to internalise, and the credit model needs one careful read before anyone forecasts a bill. | Low for engineers. The model is small: users or inline recipients, templates per channel, workflows made of nodes, providers behind them. The concepts that take longest are provider pools and which workspace a key belongs to. |
| Platforms | Web dashboard, REST API, React and React UI packages, JavaScript client, Node.js server library, Webhooks | Web dashboard, REST API, MCP server, Python and TypeScript server SDKs, JavaScript, React, and Vue web SDKs, React Native, Android, and Flutter mobile SDKs |
| Compliance | SOC 2, GDPR, HIPAA with a business associate agreement (paid add-on) | None published |
| Founded | 2021 | 2024 |
| Headquarters | Fully remote; Liveblocks Inc. is registered in Wilmington, Delaware, United States | Kochi, Kerala, India |
| Ownership | Venture-backed | Bootstrapped. Built and operated by KeyValue Software Systems Private Limited, a product engineering studio running since 2017. |
| Free tier volume | 200 custom notifications per month, collaboration notifications unlimited | None; 7-day full-feature trial only |
| First paid tier | $30 per month, or $25 per month billed annually (Pro) | $249 per month, or $208 per month billed annually (Pro) |
| Paid tier volume | $30 of monthly credits, then $0.005 per custom notification | 100,000 notifications per month on Pro |
| Self-hosting | Not offered for the hosted service; the sync engine and dev server are open source | Not offered; managed cloud only |
Strengths and limitations
Liveblocks
Strengths
- The notification tray, read state, per-user channel settings, and batching arrive as part of shipping comments and mentions, which is the work most teams were dreading anyway.
- All six delivery channels, notification settings, batching, and the pre-built components are available on the free plan, which almost nothing else in this category does.
- Collaboration notifications are unmetered on every plan, so the highest-volume notification type in a collaborative product costs nothing.
- Pro at $30 a month, or $25 billed annually, is the cheapest paid entry in the category by a very large margin.
Limitations
- Liveblocks never sends the email. It fires a webhook with the unread list and you compose and deliver the message yourself, which is real work the rest of this category absorbs for you.
- No SMS, no voice, and no mobile push beyond web push, so anything reaching a phone outside a browser needs another tool.
- Pre-built components are React. A Vue, Angular, or Flutter team gets APIs and builds the tray, which is the same complaint people make about Knock.
- The credit model pools four unrelated meters into one balance, which makes forecasting harder than a flat message allowance and hides which feature is spending the money.
Siren
Strengths
- Nine channels out of the box including WhatsApp, Discord, and LINE, which is broader than any other platform in this category at a published price.
- In-app inbox SDKs for JavaScript, React, Vue, React Native, Android, and Flutter, so teams outside the React default get a supported component rather than a REST endpoint.
- Provider pools give genuine vendor redundancy with per-provider message limits and automatic rollover, which most rivals leave as a single configured sender per channel.
- The agent surface is real and specific: an MCP server, function-calling toolkits for OpenAI, LangChain, and Vercel, and a chat node that holds a workflow open while a human answers in Slack, Teams, or Gmail.
Limitations
- No free plan at all. Seven days of trial, then $249 a month, which is the hardest entry in the category and rules out hobby projects and long evaluations.
- No batching or digest primitive anywhere in the product or the documentation, and collapsing nine events into one notification is the single most common reason teams buy a platform like this.
- 500 stored users on the published plan, with campaigns and cohorts bounded by it, so consumer-scale list work needs an Enterprise conversation immediately.
- No published compliance attestations. There is no SOC 2 report, ISO certification, or HIPAA statement in the public documentation, which will stall procurement at any regulated buyer.
Pricing compared
Liveblocks
A credit balance per month shared across every meter (collaboration minutes, comments, custom notifications, and realtime storage), with a free plan, two published paid tiers, and pay-as-you-go rates once the credits are spent.
- Free$0
- Pro$30
- TeamFrom $600
- EnterpriseCustom
Judged as notification infrastructure, Pro at $30 a month is the cheapest credible option in this category by an order of magnitude, and the free plan is genuinely usable because the channel list and batching are not withheld from it. The reason it is cheap is that the expensive part, composing and sending the email, stays with you, and the notifications that would otherwise be metered are the ones the collaboration products generate for nothing. The model breaks down in two places: the credit pool makes the bill hard to forecast if collaborative editing is heavy, and the step from $30 to $600 arrives sooner than the number suggests once a team needs SOC 2, more than three console seats, or more than ten people in one room. Buy it when collaboration is genuinely part of the product; it is poor value as a general notification router.
Siren
A single published subscription priced on notification volume, with hard caps on stored users, campaigns, team members, and log retention, sold above a seven-day full-feature trial. No permanent free tier.
- Free trial$0
- Pro$249
- EnterpriseCustom
On raw allowance Siren is the best value at its price point in this category: 100,000 notifications, unlimited workflows and templates, cohorts, campaigns, and nine channels for $249 a month, against 50,000 messages for $250 at Knock and 50,000 deliveries for $249 at MagicBell. The catch is the shape of the plan rather than the number. No free tier means you cannot prove the thing in production before paying, 500 stored users rules out consumer audiences on the published plan, and 30 days of logs is short for anything audited. For a small B2B product sending tens of thousands of notifications a month across several channels, this is the most capability per dollar on offer. For a team that wants to start at zero and grow into a bill, it is the wrong door.
Editorial verdict on each
Liveblocks
Liveblocks is the right purchase when the notifications your product needs are about people working on the same thing. Add Comments or a collaborative editor and the inbox, the unread state, the per-user channel settings, the batching, and the email digest hook arrive with it, the notifications those features generate are never metered, and the paid plan starts at $30 a month against $249 or $250 everywhere else in this category. Two things should send you elsewhere. If your notifications are billing alerts, order updates, and system warnings with no collaboration behind them, you are buying a sync engine to get a tray and Knock, Courier, or SuprSend will serve you better. And if the messages have to reach a phone by SMS or native push, Liveblocks does not go there at all. For a React product adding collaboration, it is the cheapest good answer in the category by a distance.
Read the full Liveblocks profileSiren
Siren is the pick when the notification problem has moved past email and Slack, and especially when an agent is one of the things doing the notifying. Nine channels, six front-end SDKs, provider pools that fail over between vendors, campaigns with a database connection, and an MCP server that makes a workflow trigger a tool call add up to more product than anything else at $249 a month, and the 100,000 notification allowance is twice what the two closest-priced rivals include. The reasons to walk away are concrete rather than aesthetic: no free tier means you cannot prove it in production first, there is no batching or digest primitive at all, 500 stored users bounds anything list-driven, and no compliance attestation is published. For a small B2B team sending across many channels with an agent in the loop, it is worth the trial week. For a team whose first requirement is a digest, or whose security review needs a SOC 2 report, look at Knock, Novu, or SuprSend instead.
Read the full Siren profileLiveblocks profile last reviewed 2026-09-13; Siren last reviewed 2026-09-13. Pricing is compiled from public sources and can change without notice. See our methodology.
The best in Notification Infrastructure
9 trackedNotification infrastructure platforms sit between an application and its delivery providers, turning one API call into orchestrated in-app, email, push, SMS, and chat notifications with batching, digests, preference centres, and per-tenant routing, so product teams stop rebuilding that logic in application code.
Batching, preference centres, and multi-tenancy are first-class rather than roadmap items, and workflows-as-code with environments and rollback makes a notification change a normal deploy.
$30 a month for 30,000 workflow runs, or nothing at all self-hosted, against a category whose next cheapest real plan is $110 and whose leader jumps from free to $250.
Founded in 2022 on roughly $1M, SuprSend shipped nine channels on the free tier, CLI environment promotion, an MCP server, and an Agent SDK while larger rivals were still writing about them.
The delivery planner turns cross-channel escalation into configuration: try in-app, fall back to email only if it goes unread, set as a rule rather than written as application code.
A visual designer that previews every channel on one canvas, and a bill that is $0.005 a send with no seats or channel fees, let a non-developer own the message end to end.
Frequently asked questions
6 questionsWhat is the difference between Liveblocks and Siren?
Opposite answers to who the notification is about. Siren routes across nine channels including WhatsApp, Discord, and LINE, adds provider pools and an agent toolkit, has no free tier, and starts at $249 a month. Liveblocks stops at in-app, email, Slack, Microsoft Teams, and web push, is free for 200 custom notifications a month, and generates the rest from comments and mentions at no cost. If an agent or a backend service is the sender and the channel mix is wide, Siren. If a colleague is the sender and the surface is a document, Liveblocks, for about a tenth of the money.
Is Liveblocks or Siren cheaper?
Liveblocks starts at $0 (Free), then $30 per month (Pro), or $25 per month billed annually. Siren starts at $249 per month, or $208 per month billed annually (7 days trial). The billing models differ, so the entry price is rarely the whole cost. Liveblocks pricing model: A credit balance per month shared across every meter (collaboration minutes, comments, custom notifications, and realtime storage), with a free plan, two published paid tiers, and pay-as-you-go rates once the credits are spent. Siren pricing model: A single published subscription priced on notification volume, with hard caps on stored users, campaigns, team members, and log retention, sold above a seven-day full-feature trial. No permanent free tier.
Does Liveblocks or Siren have a free plan?
Liveblocks has a free plan. Free includes 200 custom notifications a month, unlimited collaboration notifications, all six notification channels, notification settings, batching, pre-built components, 3,000 collaboration minutes, 200 comments, 3M realtime storage updates, 1 GB of realtime storage, 3 dashboard seats, and 10 simultaneous connections per room. Trial terms: No time-limited trial; the Free plan is permanent. Siren has no free plan. Trial terms: 7 days with everything unlocked, no credit card required.
Who should choose Liveblocks?
Product teams adding comments, mentions, or multiplayer editing to a web application who need the notification tray, the read state, the per-user channel settings, and the email digest hook that come with that work, and who are building in React.
Who should choose Siren?
Product and platform teams shipping multi-channel notifications where an AI agent is one of the senders, where the audience lives on WhatsApp, LINE, or Discord as well as email, or where the in-app inbox has to render in Vue, Flutter, or native Android rather than React.
What are the best alternatives to Liveblocks and Siren?
SaaSTracker profiles 9 products in Notification Infrastructure. The Summer 2026 awards in the category went to Knock (Category Leader), Novu (Best Value), SuprSend (Momentum). Every profile is compiled from primary sources, so a shortlist can be built from pricing, limitations, and fit rather than from star ratings.
