Security & Crypto Tools
API Key Format Validator
Check API keys against known provider formats (Stripe, OpenAI, GitHub…).
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What is API Key Check?
A format matcher for API keys: it compares a key's prefix and length against a table of known provider formats.
How it works
The key is matched against bundled provider rules (e.g. sk- + 51 chars for OpenAI); matches are listed with the key's length.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Checking key formats
Validate an API key against common formats — UUID, base64, hex, or a custom prefix pattern.
Common mistakes
Format is not authentication
A well-formed key passes format checks but can still be revoked or invalid server-side.
Frequently asked questions
Does matching mean the key is valid?
No — this only checks the format. A matching key could still be revoked or inactive; the tool can't call the provider to confirm.