Dev Proxy skill
A skill helps an agent configure Dev Proxy to test API errors, rate limiting and delayed responses in an application.
- 842 ★ on the repository
- Last commit
- MIT
Extended access
Why this level
- The proxy intercepts HTTPS after its certificate is trusted and can read request contents.
- Rules change application API responses, and logs can retain transmitted data.
Install
- Works in
In your terminal, with SkillFoxx CLI
npx skillfoxx add skills/dev-proxy-skillDetects the agents on your machine, shows the access level and pins the version.
Other ways to install
Access and checks
How we reviewExtended accessThe tool runs code or makes network calls and only reads external data.
- The proxy intercepts HTTPS after its certificate is trusted and can read request contents.
- Rules change application API responses, and logs can retain transmitted data.
This is third-party code. Review the repository files before installing.
What it does
The Dev Proxy skill guides an agent through network-response simulation. It selects references for mocks, application resilience or traffic inspection. Configuration combines plugins with URL-matching rules. It can reproduce API failures, throttling and slow responses while the application keeps its normal API URLs. Separate scenarios cover OpenAI-compatible requests and MCP testing. Dev Proxy itself is a local interception proxy for development.
Who it is for. For developers and QA engineers testing how an application handles external API failures.
Good fit when
- Test request retry after a throttling response.
- Check UI behavior with a slow API.
- Return predefined responses without changing application sources.
- Run repeatable integration-resilience checks in CI.
Not a fit when
- You want to increase a provider’s actual API limits.
- The environment cannot trust an interception certificate.
- Production traffic would enter an unreviewed test configuration.
Example request
Configure Dev Proxy only for the test API and verify handling of slow responses and HTTP 429.Limitations
Install Dev Proxy separately: adding the skill provides instructions but does not start the proxy. HTTPS interception requires the application to trust the Dev Proxy certificate; on Linux that trust is configured manually. An overly broad URL rule can change another API’s responses, so restrict the test to the intended application endpoints. Traffic recording can retain headers and request bodies, including sensitive data; inspect logs before sharing them with a colleague or model.
How to disable. Stop Dev Proxy and restore the test application’s proxy settings. Remove the skill from the agent; separately remove trust in the test certificate if no longer needed.
FAQ
Does Dev Proxy modify application code?
No. It intercepts network calls and changes responses according to selected rules.
Which APIs have ready-made presets?
GitHub, OpenAI, Anthropic and Microsoft Graph are documented examples for throttling scenarios.
Can it test LLM applications?
Yes. Scenarios include compatible request mocks, simulated model failures and token-based rate limiting.
Where does the agent store configuration?
In `.devproxy/` at the workspace root, together with related files.
Is there an official configuration MCP?
Yes. The project points to `@devproxy/mcp`. This separate interface requires its own installation.
Discussion
No questions or reviews yet.
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README in short
Plugins can also record requests and generate API descriptions. References separate mocking, usage analysis and CI execution.
README badge
Original SKILL.md
--- name: dev-proxy metadata: version: 1.1.0 description: "Simulate API failures, mock responses, test rate limiting, and analyze API traffic using Dev Proxy's plugin-based proxy engine. WHEN: 'mock API responses', 'simulate API errors', 'test rate limiting', 'test error handling', 'mock OpenAI responses', 'test AI app', 'analyze API usage', 'configure Dev Proxy', 'install Dev Proxy', 'set up Dev Proxy', 'use Dev Proxy in CI/CD', 'chaos testing for APIs', 'run Dev Proxy in background', 'detached mode', 'run Dev Proxy detached'." --- # Dev Proxy Dev Proxy is a command-line API simulator and proxy for testing how applications handle API failures, rate limits, latency, and more. It uses a plugin-based architecture configured through JSON configuration files. ## Prerequisites Before proceeding, verify that Dev Proxy is installed by running `devproxy --version`. If the command fails or Dev Proxy is not found: STOP — Read [references/installation.md](references/installation.md) for platform-specific installation instructions (macOS, Windows, Linux), first-run certificate setup, and verification steps. ## Quick Start Store all Dev Proxy files in `.devproxy/` in the workspace root. Start with: ```bash devproxy --config-file .devproxy/devproxyrc.json ``` STOP — Before creating or modifying any Dev Proxy configuration, read [references/best-practices.md](references/best-practices.md) for critical rules on file structure, plugin ordering, URL matching, and configuration patterns. ## Scenario Selection Identify the user's scenario and load the corresponding reference file for detailed instructions. ### Mock API Responses Return predefined responses, simulate CRUD APIs, mock MCP servers, or simulate authentication. **Plugins:** `MockResponsePlugin`, `CrudApiPlugin`, `GraphMockResponsePlugin`, `MockStdioResponsePlugin`, `AuthPlugin` STOP — Read [references/mock-api-responses.md](references/mock-api-responses.md) for mock file structure, matching rules, dynamic responses, CRUD API definitions, STDIO mocks, and auth simulation. ### Test API Resilience Simulate API failures, rate limits, throttling, and slow responses to verify error handling. **Plugins:** `GenericRandomErrorPlugin`, `GraphRandomErrorPlugin`, `RateLimitingPlugin`, `RetryAfterPlugin`, `LatencyPlugin`