Open-source API mock server for multiple protocols
Stage
Not given
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Founded
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Based in
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US
Pricing model
Freemium
Freemium
Pricing
Free for all tools. Pro: $29.99 per year or $4 per month, plus tax.
Free: $0/month with 10,000 requests/month and local mocks only. Pro: $29/month with 250,000 requests/month, 100,000 platform AI tokens/month, and 3 hosted mocks. Team: $99/month with 1,000,000 requests/month, 1,000,000 platform AI tokens/month, and unlimited hosted mocks. Annual plans include 2 mont
Key features
Validate JSON with precise line and column errors
Repair invalid JSON fixing trailing commas, quotes, and comments
Preserve large integers without rounding
Detect and mask API keys, tokens and passwords
Multi-protocol support (REST, gRPC, GraphQL, WebSocket, Kafka, MQTT and more)
Realistic data synthesis with template tokens and faker fields
Latency and fault injection for testing retries and fallbacks
Record and replay for capturing and replaying live traffic
Modern admin UI for managing servers, overrides and metrics
Configuration as code with OpenAPI specs and YAML
Local-first development without account requirement
CI integration with local endpoints
HTTP bridge exposing gRPC services over REST
BYOK AI integration with user provider keys
What makes it different
Keeps large numbers exactly as written instead of silently rounding them like most online formatters
All free tools run entirely in your browser, working offline without uploading data
Automatically detects and warns about secrets like API keys and passwords
Multi-protocol mocking from one configuration file
Realism-first simulation with data synthesis and failure injection
Open source with permissive MIT or Apache-2.0 licensing
Local-first approach with optional cloud collaboration
CurlyJSON
MockForge