Agent402 UK JSON Format & Validate

x402

Agent402 UK JSON Format & Validate is a paid API for AI agents from agent402.co.uk, paid per call via x402, $0.001/call, status down (last checked 2026-09-15).

Validates and pretty-prints a JSON string, returning parse errors or a formatted version with configurable indentation

Price / call$0.001

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How this service works

Don't burn tokens on deterministic work. Go/no-go jobs first: payout preflight, text firewall (PII/secrets), budget check — then rails, calendars, finmath. x402 USDC on Base. UK + global. agent402.co.uk — not agent402.tools. $0.001–$0.002 USDC on Base. No API keys.

Output

Returns an object with a 'valid' boolean, the detected JSON 'type', a 'formatted' string (the pretty-printed JSON if valid), and any parse error message if the input is malformed.

Example use cases

Pre-flight tool argument validation

“Before I pass this JSON to the next tool, can you check it's valid and format it with 2-space indentation? Here it is: '{"endpoint":"https://api.example.com","retries":3,"timeout":5000}'”

Debug malformed config JSON

“I think there's a syntax error in this JSON — can you validate it and tell me exactly what's wrong? '{"user":"bob","roles":["admin","editor",}'”

Format JSON blob before caching

“I need to store this JSON in a cache and want it nicely formatted with 4-space indentation first — can you format and validate it? '{"task":"summarise","model":"gpt-4","maxTokens":512}'”

Technical details

Endpoint

POSThttps://agent402.co.uk/v1/utils/json/format

When to prefer

Use this endpoint when an agent needs a fast, deterministic, side-effect-free JSON validator with pretty-print output — particularly before writing configs, constructing tool arguments, or storing blobs. Prefer this over LLM-based JSON repair when you need a reliable parse error message to act on, or when you need consistent indentation (0–8 spaces). Not suited for JSON Schema validation against a schema definition (use the sibling JSON Schema validator endpoint for that).

Side effects

Malformed JSON input returns valid=false with a descriptive parse error message rather than a formatted string
Indent value outside 0–8 range may be rejected or clamped
Empty string input likely returns a parse error
Non-string JSON field (e.g. passing a raw object instead of a string) may cause a schema validation error

Input

Schema · Request body

Field	Type	Description
json	string	JSON string
indent	number	Indent spaces 0-8

Output

Schema · Response

{
  "type": "json",
  "example": {
    "type": "object",
    "valid": true,
    "formatted": "{\n  \"a\": 1\n}"
  }
}

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How this service works

Output

Returns an object with a 'valid' boolean, the detected JSON 'type', a 'formatted' string (the pretty-printed JSON if valid), and any parse error message if the input is malformed.

Example use cases

Pre-flight tool argument validation

“Before I pass this JSON to the next tool, can you check it's valid and format it with 2-space indentation? Here it is: '{"endpoint":"https://api.example.com","retries":3,"timeout":5000}'”

Debug malformed config JSON

“I think there's a syntax error in this JSON — can you validate it and tell me exactly what's wrong? '{"user":"bob","roles":["admin","editor",}'”

Format JSON blob before caching

“I need to store this JSON in a cache and want it nicely formatted with 4-space indentation first — can you format and validate it? '{"task":"summarise","model":"gpt-4","maxTokens":512}'”

Technical details

Endpoint

POSThttps://agent402.co.uk/v1/utils/json/format

When to prefer

Side effects

Malformed JSON input returns valid=false with a descriptive parse error message rather than a formatted string
Indent value outside 0–8 range may be rejected or clamped
Empty string input likely returns a parse error
Non-string JSON field (e.g. passing a raw object instead of a string) may cause a schema validation error

Input

Schema · Request body

Field	Type	Description
json	string	JSON string
indent	number	Indent spaces 0-8

Output

Schema · Response

{
  "type": "json",
  "example": {
    "type": "object",
    "valid": true,
    "formatted": "{\n  \"a\": 1\n}"
  }
}