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PennyRail JSON Key Filter (pick--keep-json-keys)
x402
PennyRail JSON Key Filter (pick--keep-json-keys) is a paid API for AI agents from pennyrail.vercel.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).
Filters a JSON object to retain only specified keys, returning a new object containing only the picked fields
Price / call$0.001
Success—
StatusUnknown
How this service works
Machine-readable settlement service
Output
A JSON object containing only the keys that were specified in the input filter list, with all other top-level properties removed. The structure of retained values is preserved as-is.
Example use cases
Trim API response before storage
“I'm getting back huge JSON objects from the weather API — can you filter them down to just 'temperature', 'humidity', and 'wind_speed' before we save anything?”
Extract user profile fields
“From this raw user record, pick out only 'id', 'username', and 'avatar_url' — I don't want the rest of the data passed downstream.”
Sanitize webhook payload
“This incoming webhook payload has a lot of noise. Can you keep only 'event', 'timestamp', and 'payload' keys and discard everything else?”
Technical details
Endpoint
POSThttps://pennyrail.vercel.app/api/p/nano/json.pick--keep-json-keysWhen to prefer
Use this endpoint when you need a lightweight, pay-per-call JSON key filtering operation without standing up your own transformation logic. Ideal for agent pipelines that need to slim down API responses or sanitize payloads before passing data to downstream steps. Prefer this over general-purpose code execution when you want a simple, stateless field-picker with minimal overhead.
Side effects
- Missing 'input' field returns validation error
- If no matching keys exist in the object, returns an empty object
- Nested key paths may not be supported — only top-level keys may be filterable
- Payment failure (402) if USDC balance is insufficient
- Malformed JSON input may result in a 400 error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Output
Schema · Response
{
"type": "object",
"additionalProperties": true
}Tags
x402
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