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PennyRail JSON Pick – Select Object Keys
x402
PennyRail JSON Pick – Select Object 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).
Accepts a JSON object and returns a new object containing only the specified subset of keys (pick/select operation)
Price / call$0.001
Success—
StatusUnknown
How this service works
Machine-readable settlement service
Output
Returns a new JSON object containing only the key-value pairs from the input object whose keys were specified in the selection. All other keys from the input are omitted. The response is a plain JSON object with the picked fields.
Example use cases
Trim API response to essential fields
“I'm getting back a huge user object from our auth API — can you pick just the 'id', 'email', and 'displayName' fields from it so I can pass a smaller payload to the next step?”
Project config object for downstream service
“Here's a big config JSON with dozens of keys. I only need to forward 'host', 'port', and 'timeout' to the connection service — can you select just those keys from the object?”
Extract billing fields from invoice record
“I have a full invoice record as a JSON object. Can you pick out only the 'invoiceNumber', 'amount', 'currency', and 'dueDate' fields so I can feed them into the billing report?”
Technical details
Endpoint
POSThttps://pennyrail.vercel.app/api/p/nano/json.pick--select-object-keysWhen to prefer
Use this endpoint when you need a lightweight, paid micro-service to programmatically project a subset of keys from a JSON object — especially in agent pipelines where you want a deterministic, stateless transformation without running custom code. Prefer this over general-purpose code execution when you want a simple, auditable pick operation with a clear x402 payment trail at $0.001 per call.
Side effects
- Missing 'input' field in request body returns a validation error
- If requested keys do not exist on the input object, those keys are silently omitted from the result
- Malformed JSON body causes a parse error
- Payment failure or insufficient USDC balance blocks the request via x402 payment protocol
- Empty key selection may return an empty object
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Output
Schema · Response
{
"type": "object",
"additionalProperties": true
}Tags
x402
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