Kaja: gRPC & OpenAPI Client
Built for you and your agents
Only for Mac
Free
Mac
Kaja is the API client built for you and your agents.
Connect gRPC, OpenAPI, or MCP. Explore APIs yourself, or let an agent write and run typed scripts. Every request stays visible and inspectable.
CONNECT. RUN. INSPECT.
One window: your APIs on the left, the script in the middle, and every call it made underneath.
CONNECT YOUR API
- gRPC through server reflection or your .proto files, with TLS and credentials per app
- OpenAPI 3.0 and 3.1 from a URL, a file, or pasted text
- MCP servers, whose tools, prompts and resources become methods you can call
- Twirp through its address and your .proto files
Browse every service and method in one tree.
RUN IT YOURSELF OR ASK AN AGENT
- Click a method and Kaja drafts the call as a typed TypeScript script
- Autocomplete for every request field, straight from the API's own types
- Chain calls, loop over pages, and ask for input as the script runs
- Draw tables and text on a canvas instead of reading raw JSON
- Approve a call before it is sent
- Run a load test and read latency percentiles, throughput and errors
- Save scripts as plain files in a folder you choose
SEE EXACTLY WHAT HAPPENED
Requests, responses, headers, duration and status stay visible for every run. The log keeps every call in order, and the canvas shows what the script drew.
AGENTS CAN DO THE WORK WITHOUT BECOMING A BLACK BOX
Kaja includes an MCP server for the APIs you connected. Point Claude Code, Codex, Cursor, VS Code or any other MCP-capable agent at it. The agent writes TypeScript against your APIs and runs it through Kaja. Every request it makes appears alongside your own.
SECRETS STAY OUT OF YOUR FILES
Keep a token in the macOS Keychain or the environment. Your workspace file only names it.
YOUR WORKSPACE, YOUR FILES
Everything lives in one kaja.json and a folder of scripts, so a workspace can be committed next to the code it tests. Kaja collects no data.
Kaja is open source. Documentation and a live demo are at kaja.tools.
- This app hasn’t received enough ratings or reviews to display an overview.
MCP app promoted to stable
The developer, Tomas Vesely, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Tomas Vesely
- Size
- 18.2 MB
- Category
- Developer Tools
- Compatibility
Requires macOS 12.0 or later and a Mac with Apple M1 chip or later.
- Mac
Requires macOS 12.0 or later and a Mac with Apple M1 chip or later.
- Mac
- Age Rating
4+
- 4+
- Copyright
- © 2026 Tomas Vesely