Free responsive website checker for mobile, tablet and desktop
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
Free
Freemium
Pricing
Not given
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
Test multiple device viewports simultaneously
Real CSS viewport rendering
Share setup links
Custom pixel width testing
No installation required
Sync scroll across panes
Browser-based with no account needed
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
Compare multiple real device widths side by side instead of switching one at a time
Faster than DevTools for checking several device sizes at once
Entirely browser-based with no setup, signup or download
Built and maintained by one developer in the open
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
Responsive Tool
MockForge