Duplicate JSON object keys found in raw text, before a parser drops them
Scans raw JSON text (RFC 8259) for repeated object member names at any depth, including inside arrays and keys spelled differently but equal after unescaping ("a" vs "\u0061"), and reports each with its JSON pointer, UTF-8 byte offset, line, column and the value every occurrence carried, plus whether the values conflict. Also reports a leading BOM, unpaired surrogates, __proto__ keys and the exact syntax error offset. For agents that must inspect JSON before JSON.parse, json.loads or a gateway silently keeps the last duplicate. It does not validate against a schema and does not repair the text.
What you get
Parsers disagree on duplicate keys (last wins, first wins, error), so the same bytes can mean different things to two systems. 200 KB per $0.005 call.
Call it
Send the JSON body below to https://agents.writerslogic.com/api/v1/duplicate-key-audit. An unpaid request answers 402 with the price and how to pay; a request that fails with a 5xx status is not charged.
curl -i -X POST https://agents.writerslogic.com/api/v1/duplicate-key-audit \
-H 'content-type: application/json' \
-d '{"text":"{\"id\": 1, \"items\": [{\"sku\": \"a\", \"sku\": \"b\"}], \"id\": 2}"}'
Input
| Field | Type | Required | Description |
|---|---|---|---|
text | string; length 0..200000 | yes | Raw JSON text, up to 200000 characters and 64 levels of nesting. |
Example request body
{
"text": "{\"id\": 1, \"items\": [{\"sku\": \"a\", \"sku\": \"b\"}], \"id\": 2}"
}
Result
The response is { "data": ..., "_provenance": ... }. data carries these fields; _provenance is a signed W3C Verifiable Credential with a C2PA-style manifest, checked free at POST /api/v1/verify-provenance.
| Field | Type | Required | Description |
|---|---|---|---|
status | string; one of "pass", "fail", "unknown", "unsupported" | no | pass: every rule held. fail: a rule was violated (see witnesses). unknown: the input lacks the evidence to decide. unsupported: outside what this engine covers. Missing evidence is never a pass. |
validSyntax | boolean | no | True when the text is strict RFC 8259 JSON (a BOM makes the bytes non-conforming but is reported separately). |
bom | boolean | no | |
duplicateCount | integer | no | |
duplicates | array<object> | no | |
hazards | array<object> | no | |
syntaxError | one of | no | |
witnesses | array<object> | no | |
versions | object | no | Every semantic dependency of this answer (engine, tables and their as-of dates, tokenizer, calendar, rounding profile). |
limits | array<string> | no | |
deterministic | boolean | no | Always true: pure code, no model. |
Pay and connect
Available through: x402 (USDC on Base), MCP. MCP clients reach it through the data-contract-kit package.
Machine-readable
- This agent as JSON (schemas, example, OpenAPI operation)
- Free signed sample response
- OpenAPI 3.1 · Catalog · Index of every agent