Cap'n Web

lastmod 2025-09-25created 2025-09-251 edits

Cap'n Web, a new RPC system for browsers and web servers

About

• Cap'n Web is a new RPC protocol implemented in TypeScript, optimized for the web and running on various JavaScript runtimes
• Provides JSON-based serialization and a human-readable data format, with no schemas or tedious boilerplate
• Its object-capability model enables bidirectional calls, passing function and object references, promise pipelining, and implementing security patterns
• Supports various network environments such as WebSocket, HTTP, and postMessage, and is lightweight open source under 10kB
• Not only solves the waterfall problem much like GraphQL, but also enables natural RPC modeling that feels like an ordinary JavaScript API

See also

• Cap'n Proto
• Serialization

Favorite site

• Cap'n Web: a new RPC system for browsers and web servers
• Cap'n Web, a new RPC system for browsers and web servers | GeekNews