Last updated: July 26, 2026
API Contract Guardian is a Chrome DevTools extension for inspecting API traffic, monitoring JSON contract changes, identifying page-data endpoints, and building payload extraction recipes.
Data processed locally
Guardian processes network request metadata, URLs, request and response headers, request bodies, response bodies, JSON schemas, extraction recipes, and user-entered investigation prompts. Capture, contract comparison, deterministic ranking, and extraction occur inside the extension.
Captured response bodies are held in memory for the active DevTools session and are not persisted.
Data stored on the device
Chrome local storage contains settings, saved contract baselines, optional provider API keys, a random installation identifier, and Lemon Squeezy license state. Removing the extension deletes this storage.
Optional AI providers
Ollama
Ollama requests go only to the locally configured Ollama endpoint.
Cloud providers
If the user selects OpenAI, Anthropic Claude, OpenRouter, or ZenMux, Guardian sends the minimum data required for the user-requested analysis. Contract analysis sends endpoint and schema-change information. API Finder may send captured URLs, redacted request bodies, bounded redacted response excerpts, compact schemas, and the user's question and examples.
API Finder requires explicit acknowledgement before every external submission. Secret-like fields and query parameters are redacted. Authorization and cookie headers are excluded. Each provider's own privacy terms apply.
Lemon Squeezy licensing
Activation, validation, and deactivation send the entered license key and a randomly labeled installation instance to Lemon Squeezy. Guardian stores the key, instance identifier, product/variant label, expiration date, and last successful validation time locally. Customer names and email addresses returned by the service are not stored.
Retention and deletion
- Current capture data is removed when a new page session begins or the user selects Clear.
- Response bodies are not saved to extension storage.
- Contract baselines remain until overwritten, cleared with extension storage, or the extension is removed.
- Deactivating Pro removes local license state and releases the Lemon Squeezy instance.
Guardian does not sell personal data, use captured traffic for advertising, or transmit it to the publisher.
Chrome permissions
| Access | Purpose |
|---|---|
storage | Settings, baselines, optional keys, and license state. |
| Local Ollama hosts | User-initiated local AI requests. |
| Selected AI hosts | User-initiated analysis with the provider chosen by the user. |
| Lemon Squeezy API | Activate, validate, and deactivate Pro licenses. |
Guardian does not request tabs, activeTab, scripting, cookies, downloads, clipboard permissions, webRequest, or access to every website.
Contact
Publisher: Built by Kris
Email: support@builtbykris.com
Website: builtbykris.com