Dev Cheatsheet — HTTP, MIME, Key Codes & Regex

What is Dev Cheatsheet — HTTP, MIME, Key Codes & Regex?

Dev Cheatsheet is a free, in-browser quick reference that bundles four developer lookup tables into one searchable widget. Front-end and back-end developers, QA engineers, and students reach for it when they need to remember what 422 means, the MIME type for a .webp image, the key value an arrow press fires, or a regex for validating an email. The HTTP tab lists common 2xx, 3xx, 4xx, and 5xx status codes with their official reason phrases; the MIME tab maps file extensions to Content-Type values; the Key codes tab shows JavaScript KeyboardEvent.key strings such as Enter, Escape, and ArrowUp; and the Regex tab collects ready-to-paste patterns with a short note on each. The search box filters the active tab instantly, the result count tells you how many entries match, and every row exposes a copy button. The combined output box serializes the filtered rows so you can pipe them into another tool. Because the widget renders only with JavaScript, this text is the indexable description: an HTTP status code reference, a MIME type table, a JavaScript key code list, and a regex cheatsheet, all client-side.

How to use Dev Cheatsheet — HTTP, MIME, Key Codes & Regex

1. Pick a tab: HTTP status, MIME types, Key codes, or Regex.
2. Type in the search box to filter the active tab by code, label, or pattern.
3. Scan the rows and read the result count to see how many entries match.
4. Click Copy on any row to copy its value (label, MIME type, key, or pattern).
5. Use the Output box's Copy button to grab every filtered entry at once.

Examples

Search: 429

429  Too Many Requests

Search: webp

.webp  image/webp

Tab: Regex, Search: email

^[^\s@]+@[^\s@]+\.[^\s@]+$

Frequently asked questions

Which HTTP status codes are included?

The most common ones across all classes: 2xx success (200, 201, 204), 3xx redirects (301, 302, 304, 307, 308), 4xx client errors (400, 401, 403, 404, 405, 409, 410, 418, 422, 429), and 5xx server errors (500, 501, 502, 503, 504), each shown with its standard reason phrase.

What is the difference between the key value and the key code?

This tool lists the modern KeyboardEvent.key string, which is the human-meaningful value of a key — for example Enter, Escape, or ArrowUp. The Space key reports a single space character, shown here as the ␣ symbol. The key string is what you compare against in event handlers like event.key === 'Enter'.

Can I use these regex patterns directly?

Yes. Each pattern is written in standard JavaScript regular-expression syntax, ready to paste into new RegExp('...') or between slashes. They are practical starting points — for example a simple email or URL check — not exhaustive validators, so review them for your exact requirements.

How does the search work?

Search filters only the active tab and matches anywhere in a row: the code, the label, the MIME type, the key, the regex title, or the pattern itself. It is case-insensitive, so typing 'JSON', 'not found', or '404' all narrow the list immediately, and the result count updates live.

Is anything sent to a server?

No. Every table is a static list baked into the tool, and all filtering and copying happen entirely in your browser. Nothing you search for is uploaded, logged, or sent anywhere, so the cheatsheet works offline once loaded.