Realtime Transport · decision tool
WebSockets vs SSE vs polling — which realtime transport?
Answer direction, serverless deployment, update frequency and simplicity — get a capability-fit verdict across WebSockets, Server-Sent Events, long polling and a managed realtime service. Documented facts only; the 'websockets on serverless' constraint is front and center.
Capabilities verified 2026-07-17 against official documentation · fit weights are our estimates (see methodology) · share the URL to share your configuration
As of Jul 2026, for this page's default requirements, Server-Sent Events (SSE) is the conditional pick at 89% capability fit (Long polling: 84%). This is a capability-fit decision, not a price ranking — StackSays does not invent a unified dollar comparison across these tools' incompatible billing units. Change any requirement below and the verdict recomputes.
Your requirements
The verdict updates as you change these. Share the URL to share your answers.
Conditional pick
Server-Sent Events (SSE) (89% fit)
Ranked by capability fit
Server-Sent Events (SSE) vs Long polling — the tradeoffs that decide it
- Update latency: Server-Sent Events (SSE) — Instant push suits frequent updates. Long polling — Polling is adequate for frequent-but-not-instant.
When to pick Long polling instead: when the lines above where it leads matter more to you than the ones where Server-Sent Events (SSE) leads. Change the inputs to see the ranking flip.
This is a capability-fit decision, not a price ranking — these tools bill in incompatible units (per-search vs per-RAM cluster vs per-PB scanned) and several publish rates only in their own calculators, so StackSays does not invent a unified dollar comparison. Every score above traces to a documented capability; see Data sources below.
At a glance
| Tool | Deployment | Open source | Verified |
|---|---|---|---|
| WebSockets | Self-hosted | Yes | 2026-07-17 |
| Server-Sent Events (SSE) | Self-hosted | Yes | 2026-07-17 |
| Long polling | Self-hosted | Yes | 2026-07-17 |
| Managed realtime (Pusher / Ably / Supabase Realtime) | Managed only | No | 2026-07-17 |
Data sources
| Tool | Source | Verified |
|---|---|---|
| WebSockets | MDN WebSockets API (capabilities) | 2026-07-17 |
| Server-Sent Events (SSE) | MDN Server-Sent Events (capabilities) | 2026-07-17 |
| Long polling | MDN Fetch/HTTP (polling uses standard requests) | 2026-07-17 |
| Managed realtime (Pusher / Ably / Supabase Realtime) | Pusher Channels docs (managed realtime capabilities) | 2026-07-17 |
A monitor re-checks these pages for changes; when a vendor moves a price, the date updates and every verdict recomputes.