ProjectMiddleware is a Kotlin/Ktor API transformation service. It lets you define mapping rules that call an external API and reshape its JSON response — so every client gets exactly the format it needs, without touching the upstream service.
Full documentation: leonardobai12.github.io/ProjectMiddleware
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Define mapping rules — specify which external endpoint to call and how to transform its response: rename fields, extract nested values, concatenate multiple fields, and more. See Mapping Rules.
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Preview before committing — call
/v1/previewwith your rules to verify the transformed output before creating a permanent route. See Preview Route. -
Create the mapped route — once the preview looks right, register the route. It gets a UUID-based path and stays live from that point on. See Mapping Request.
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Call the route — send requests to
/v1/{uuid}/{path}and receive the transformed response in real time.
- Flexible field mapping — rename fields, extract values from deeply nested structures, and concatenate multiple fields into one.
- Preview before creation — validate mappings against live data before committing to a permanent route.
- Dynamic routing — every registered route is served instantly via its UUID path with no redeployment needed.
Base URL: https://projectmiddleware.fly.dev/
| Method | Path | Description |
|---|---|---|
POST |
/v1/mapping |
Create a mapped route |
GET |
/v1/routes |
List all mapped routes |
POST |
/v1/preview |
Preview a mapped response |
* |
/v1/{uuid}/{path} |
Call a mapped route |
For a complete list of routes and ready-to-run examples, see the Postman collection.