Deterministic · Source-visible · Agent-ready

Repair the JSON your model almost returned.

JSONSuture fixes common syntax damage, validates the result against JSON Schema, and reports what changed—without another model call or retained payload.

Create a free API key See the benchmark

A small, inspectable reliability boundary

Deterministic repair

Common fences, quotes, comments, commas, and truncation are handled predictably. No model retry means no changed answer.

Schema-aware

Validate JSON Schema and opt into type coercion or defaults. Semantic mismatches remain visible.

Source-visible core

Read the repair adapter, tests, benchmark, limits, and threat model before trusting the hosted endpoint.

14/14 documented acceptance cases pass

The reproducible suite covers six repair shapes, four schema behaviors, and four guardrail outcomes. It is a fixed acceptance suite—not a claim about every corruption and not a competitor comparison.

Review every case and reproduce it locally

One request

curl -X POST https://vesper-3159a405.base44.app/functions/v1RepairJson \
  -H "Authorization: Bearer $JSONSUTURE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"text":"{name: Ada, active: true,}","schema":{"type":"object"}}'

Know the boundary

JSONSuture repairs structure; it does not invent missing facts. If you need token-by-token streaming repair, use a streaming-specific system. If plain prose must never be accepted, provide an object or array schema so validation rejects it.

A low-cost path between free and high volume

Free

250 requests/month
10 requests/minute
No card required

Developer

$9 / month

10,000 requests/month
60 requests/minute
Secure billing portal

Start Developer

Pro

$29 / month

100,000 requests/month
300 requests/minute
Secure billing portal

Start Pro

Subscriptions renew monthly until canceled. Manage or cancel through the Stripe-hosted customer portal.

Start with the failure mode

The practical guide covers when deterministic repair is safe, when a schema is mandatory, and when you should retry the model instead.

Read: How to fix malformed LLM JSON without a retry loop

Terms of service

JSONSuture is provided on a best-effort basis without warranties. Customers must not use the service for unlawful activity or process data they are not authorized to handle. Published quotas, rate limits, and abuse controls apply. Paid subscriptions renew monthly and may be canceled before the next billing date to prevent future charges.

Privacy

JSON request payloads and schemas are not retained. The service stores hashed API keys, plan status, coarse usage counters, request latency, status, and estimated infrastructure cost for authentication, billing, abuse prevention, and reliability. The service does not create advertising profiles or sell customer data.

Support

For implementation, billing, or private security support, email darkstorm13@gmail.com. Use the issue tracker only for non-sensitive bugs and feature requests. Never include API keys, credentials, or private payloads.