// the take
Swell is an Electron desktop app that does for streaming protocols what Postman does for REST: it lets you fire requests and watch live traffic over HTTP/2, SSE, WebSockets, GraphQL, gRPC, tRPC, and WebRTC, plus assertion scripting and basic load testing. It's aimed at backend/full-stack developers building or integrating real-time APIs who are stuck using curl, wscat, or grpcurl for lack of a GUI that covers more than REST.
Protocol coverage is genuinely broad and specific, not just marketing: all four gRPC streaming modes, tRPC with correct batching semantics for mixed query/mutate calls, and GraphQL subscriptions plus introspection are things Postman and Insomnia still handle inconsistently. The built-in Chai-style assertion scripting and HTTP/2 and GraphQL stress testing mean you can write pass/fail checks and do a quick load test without wiring up a separate tool like k6. Workspaces persist locally via IndexedDB with import/export, so there's no forced account or cloud sync to use the thing. The HTTP/2 mock server is a real convenience for frontend work against an API that doesn't exist yet.
The assertion/scripting feature runs user scripts through vm2, which is deprecated and has multiple unpatched sandbox-escape CVEs; running arbitrary test code through it inside an Electron app with filesystem access is a real liability, not a theoretical one. WebRTC testing is manual SDP copy-paste between two running instances with no signaling server, so it's a one-off exercise rather than something you'd use repeatedly. The maintainers themselves flag the mock server, webhooks, and OpenAPI support as experimental, so the long tail of protocols is noticeably less baked than the headline HTTP2/GraphQL/WebSocket support. It's an Electron app competing with native and web-based alternatives, and the 80+ one-time contributor list (reads like a bootcamp capstone lineage) is a yellow flag for how long fixes keep landing after the current maintainers move on.
We read the README, the directory tree and a key source file in October 2026. Nobody pays to be listed. How we judge →