JSON Validator API

io.github.Br0ski777Published by GitHub account Br0ski777v1.1.0Updated Oct 24, 2026

JSON syntax validation, JSON Schema checking, structure stats. x402 micropayment.

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Overview

AI-generated overview

A remote MCP endpoint that lets an assistant validate JSON syntax and check JSON data against a JSON Schema, paid per call in USDC.

What you can do
Validate a JSON string for syntax errors and get back validity status, parse errors and formatted JSON. Optionally check the same data against a supplied JSON Schema. Receive structure statistics such as depth, key count, array count and total size. The README notes it is not intended for password checks, hash generation or cron parsing, which it points to other services for.
When to use it
Useful when an assistant needs to confirm that generated or pasted JSON parses and conforms to a schema, and when a pay-per-call service is preferable to running a validator locally.
Requirements
A remote MCP endpoint reached over SSE; no package install. No API key or signup is declared. Calls are paid per request through the x402 protocol in USDC on the Base L2 network, so an x402-capable client with a funded wallet is needed. Network access to the provider's host is required.
Before you install
Each validation call costs money (listed at $0.003 per call) in USDC on Base, settled through a wallet; the assistant or client must be able to sign x402 payments. The JSON and optional schema you submit are sent to a third-party service. Payment goes through Coinbase CDP and PayAI facilitators. Treat the price and network details as the provider's claims and verify them before use.

Installation

In SourceWeft

  1. Open JSON Validator API in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Web executable via SSE. Remote servers run from the web runtime once configured in a workspace.

Use with an agent

Paste this prompt into Claude Code, Codex, Cursor or another agent — or into SourceWeft chat. The agent reads this server's install guide, shows you its publisher, endpoint and sign-in, and adds it to your client once you agree. Keys never go into a command.

Read https://sourceweft.com/mcp/io.github.Br0ski777%2Fjson-validator/install.md and connect the MCP server it describes to my client. Before changing any config, show me its publisher, endpoint and sign-in method and wait for my OK. Never put an API key in a command or in a file I would commit; ask me where it should come from.

Read the install guide the agent follows

Other MCP clients

Add this to your client's mcpServers config.

{
  "mcpServers": {
    "json-validator-api": {
      "type": "sse",
      "url": "https://json-validator.api.klymax402.com/mcp"
    }
  }
}

README

JSON Validator API

[MCP Server] [x402] [License: MIT]

JSON validator with optional JSON Schema validation and structure stats. Pay-per-call via x402 (USDC on Base L2) -- no API key, no signup, no rate-limit wall.

Part of the klymax402 marketplace -- 100 x402 micropayment APIs for AI agents, one wallet, USDC on Base.

Quickstart -- MCP

Add to your MCP client config (Claude Desktop, Cursor, ElizaOS, etc.):

json
{  "mcpServers": {    "json-validator": {      "url": "https://json-validator.api.klymax402.com/mcp"    }  }}

Quickstart -- HTTP (x402)

bash
curl -X POST "https://json-validator.api.klymax402.com/api/validate" \  -H "Content-Type: application/json" \  -d '{"json":"..."}'# -> 402 Payment Required, with an x402 payment challenge in the response body

Any x402-aware client (@x402/fetch, x402-agent-tools, ATXP) handles the 402 -> sign -> retry cycle automatically.

Tools

ToolMethodPathPriceDescription
data_validate_jsonPOST/api/validate$0.003Validate JSON and optionally check against a JSON Schema

data_validate_json

Use this when you need to validate JSON syntax or validate JSON data against a JSON Schema. Returns validity status, parse errors, formatted JSON, and structure stats (depth, key count, arrays, total size). Do NOT use for password checking — use security_check_password. Do NOT use for hash generation — use crypto_generate_hash. Do NOT use for cron expressions — use util_parse_cron.

Parameters

NameTypeRequiredDescription
jsonstringyesJSON string to validate
schemaobjectnoOptional JSON Schema to validate against

Example agent prompts

  • "Validate JSON syntax or validate JSON data against a JSON Schema"

Payment

  • Protocol: x402 -- HTTP-native pay-per-call, no signup, no API key
  • Network: Base L2 (eip155:8453)
  • Asset: USDC
  • Facilitator: Coinbase CDP (primary), PayAI (fallback)

Part of klymax402

100 x402 micropayment APIs for AI agents -- one wallet, USDC on Base, zero signup.

License

MIT

Source: README.md at commit f7bf3e9

Tools

0
SourceWeft has not read this server's tools yet.

Version history

1
  1. v1.1.0LatestSep 16, 2026

Score

50% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 daysRequired25 pts

    Keep the endpoint answering the MCP handshake; SourceWeft probes it every 30 days.

  • Auth declaredRequired10 pts

    Declare the credential headers in the registry entry, or keep the endpoint answering the probe so its auth can be classified.

  • Tools listed15 pts

    Answer tools/list without a credential, or ship a package that starts in a sandbox without one.

  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts
  • License10 pts