Dev
Mock Server-Sent Event Generator
Used by developers, writers, and creators worldwide.
A mock Server-Sent Event generator produces example SSE streams for testing real-time features. Server-Sent Events are a simple way for a server to push updates to a browser over a single long-lived connection, and the wire format is specific — id, event, and data fields separated by blank lines. When you build or test an SSE client, you need realistic sample events without standing up a streaming server. This tool emits a correctly formatted stream with multiple events, each carrying an id, an event type, and a JSON data payload. Choose how many events you want and copy the stream. It is ideal for testing SSE parsing, building a mock streaming endpoint, and learning the SSE format. The output follows the real protocol — note the blank line that separates each event, which clients rely on to know an event is complete.
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How to use
- Choose your options above
- Click Generate
- Copy your result
Detailed instructions
- Choose how many events you want.
- Click Generate to produce an SSE stream.
- Copy it into your test or mock endpoint.
- Use it to exercise your SSE client.
Use Cases
- •Testing an SSE client parser
- •Building a mock streaming endpoint
- •Learning the Server-Sent Events format
- •Seeding sample real-time data
- •Demoing a live-update feature
Tips
- →Each event ends with a blank line.
- →SSE is one-way, server to client.
- →The data field here carries JSON.
- →Test parsing before wiring a live stream.
FAQ
what are Server-Sent Events
Server-Sent Events are a standard for a server to push updates to a browser over one long-lived HTTP connection. Unlike WebSockets, they are one-way and text-based, with a simple format of id, event, and data fields, making them ideal for live feeds.
why do events have a blank line
The blank line separates one event from the next and signals that an event is complete. SSE clients rely on it to know when to dispatch an event, so the format requires a blank line between each event block.
how is SSE different from WebSockets
SSE is one-way — server to client — and runs over plain HTTP with automatic reconnection, which makes it simple for live updates like notifications or progress. WebSockets are two-way and better suited to interactive, bidirectional communication.