Connect to an SSE endpoint and display incoming events in real time with event type filtering.
SSE servers push events over a single long-lived HTTP connection, and this tool puts that stream on screen: enter an endpoint URL, connect, and every incoming event is listed with its event type and payload, with a filter that shows only the type you care about. The catch is that it sees the stream the way a browser EventSource does. Events only fire when a blank line terminates them, an event with no event: field is type message, and the endpoint must allow the tool's origin. An endpoint that works in curl can still refuse this connection.
A concrete input and expected output from the current implementation.
Input
Endpoint URL: https://example.com/events
Wire data the server then sends:
event: tick
data: {"price":100.25}
event: tick
data: {"price":100.50}
data: {"status":"ok"}
Expected output
Three events, one per blank-line-terminated block:
- tick / {"price":100.25}
- tick / {"price":100.50}
- message / {"status":"ok"}
The third is type message because its block has no event: field. With the type filter set to tick, the list shows only the two tick events. Each blank line ends one event, so the three blocks produce exactly three events. The event: field names the type, and a block without one falls back to the default type message, which is why the third entry is labeled message; the filter then matches against that type string.
The tool makes a plain HTTP GET to the URL you enter; the endpoint answers with Content-Type: text/event-stream and keeps the socket open, pushing lines as they occur. If the connection drops, the client reconnects automatically, honoring a server-supplied retry: field. Events tagged with id: let it resume by sending a Last-Event-ID header. Browser rules still apply: the endpoint needs CORS headers for the tool's origin.
The stream is split into blocks of field: value lines by blank lines. data: lines accumulate into the event payload, joined with newlines when repeated. event: names the event type, and a block without one defaults to message. A blank line terminates the block and dispatches the event, which the tool lists as type plus payload. Colon-prefixed lines are comments, ignored but useful as keepalives.
No. Server-sent events are a plain GET with standard headers, and a browser-based client cannot attach Authorization or a body. If the endpoint demands a token, you need a cookie the browser already carries, a token in the URL, or a different transport such as WebSocket.
Three usual causes, in the order to check them: the endpoint lacks CORS headers for the tool's origin; events are not blank-line terminated, so none ever dispatch; or an intermediary buffers the stream, so chunks arrive late here while curl, run locally, gets them instantly. Fix each at its source before suspecting the endpoint's data.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
Format, validate, and beautify JSON with syntax highlighting and error detection.
Encode text or files to Base64 and decode Base64 strings back to their original form.
Format and indent SQL queries for better readability across all major dialects.
Convert HTML markup into clean Markdown syntax with support for tables and lists.
Write Markdown and see the rendered HTML output in real time with live preview.
Visualize unified diffs and patch files with color-coded additions and deletions.