FieldFlow
Turn your REST API into an optimized MCP Server
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FieldFlow converts any OpenAPI-described REST API into a filtered MCP server with FastAPI routes.
- for
- Developers building LLM agents or apps that need field-level API responses.
- license
- MIT
- v0.1.0FieldFlow v0.1.07 months ago
Key features
- OpenAPI native — Point FieldFlow at an OpenAPI 3.x spec and it auto-discovers endpoints and schemas.
- Typed Pydantic models — Generates request/response models with full validation, aliases and nested refs.
- Selective responses — Each route accepts a fields list so callers receive only the data they request.
- FastAPI gateway — Proxies calls via httpx and serves filtered results through FastAPI routes.
- Spec-first fidelity — Handles recursive schema resolution to stay aligned with the upstream API.
- Optional MCP layer — Exposes the same filtered endpoints to Model Context Protocol clients like Claude Desktop.
Use cases
- Create a GraphQL-like endpoint for LLM agents without rewriting the backend.
- Reduce token consumption by returning only needed fields to LLMs.
- Expose existing REST services to Model Context Protocol clients such as Claude Desktop.
- Generate type-safe Pydantic models for rapid API integration.
- Add field-level filtering to any third-party REST API in minutes.
FieldFlow vs alternatives
 FieldFlow |  Postman |  Insomnia |  Bruno |  Smithery | |
|---|---|---|---|---|---|
| Best for | Selective field fetching for LLM agents | API design & testing | API client & testing | Git-friendly API client | MCP server discovery |
| Pricing | Free | Subscription | Free | Free | Free |
| DevHunt upvotes | 0 | 0 | 0 | 0 | 0 |
| Launched | Jan 2026 | — | — | — | — |
- FieldFlow vs Postman: Postman is a full API design, testing and documentation platform, not a selective field proxy.
- FieldFlow vs Insomnia: Insomnia provides REST/GraphQL clients and testing, but does not generate MCP servers.
- FieldFlow vs Bruno: Bruno is an offline-first API client focused on request management, not on automatic field filtering.
- FieldFlow vs Smithery: Smithery is a registry for MCP servers, while FieldFlow creates the MCP server itself.
FieldFlow FAQ
Do I need to modify my existing API to use FieldFlow?+
No, FieldFlow works as a proxy and requires no changes to the upstream REST service.
How does FieldFlow reduce token usage for LLMs?+
Agents can request only specific fields, so unnecessary payloads are omitted, cutting token count.
What format does FieldFlow accept for API specifications?+
It accepts OpenAPI 3.x JSON or YAML files.
Can I expose the filtered endpoints to Model Context Protocol clients?+
Yes, an optional MCP layer can be generated to serve the same filtered routes to MCP clients.
What Python libraries does FieldFlow rely on?+
It uses FastAPI for routing, httpx for proxying, and Pydantic for model generation.
Summarized by DevHunt from fieldflow.dev · Oct 4, 2026. Details may change; check the official site.
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