FEKit

Decode JWTs, encode URLs and Base64, format JSON, convert dates and colors, and convert, resize or optimize images in a side panel.

Twelve converters front-end developers reach for every day, in a side panel right next to the page you're working on. Encode & decode • JWT decoder — Shows the header and payload, with exp and iat as Korea time (KST) and relative time such as "30 minutes ago". A badge tells you whether the token has expired. • URL encode / decode — Works on a single query value or a whole URL. Type on either side and the other side updates. • Base64 — Converts UTF-8 text (including Korean and emoji) correctly, with a URL-safe option. • HTML entities — Escapes text to entities like < and & and back. Images • Image format converter — Converts to PNG, JPG or WebP and shows the size change against the original. Download several files at once as a zip. • Image resize & compress — Resize by width, height or percentage, and get @1x, @2x and @3x versions in one go. • Image ↔ Base64 — Generates a Data URI, CSS background and img tag, and previews Base64 as an image. • SVG optimizer — Removes comments, metadata and editor attributes to shrink the file, and exports PNG or CSS-ready code. JSON & dates • JSON formatter — Pretty-print, minify, sort keys and browse as a tree. Large integers and long decimals keep every digit, and syntax errors point to the exact line and column. • Date & timestamp — Converts between Unix seconds or milliseconds, ISO 8601 and Korea time. Web & design • URL parser — Splits a URL into its parts and decodes query values. • Color converter — Converts between HEX, RGB, HSL and OKLCH. How to use 1. Click the FEKit icon in the toolbar to open the side panel. 2. Pick a tool from the list or search for one (⌘K / Ctrl+K). 3. Paste a value to see the result instantly, then copy it with the Copy button. Star the tools you use most to pin them to the top as favorites. Privacy Everything you enter, including images, is processed on this computer and never sent anywhere. Input is not saved and disappears when you close the panel. The only things stored are the names of your favorite and recently used tools. FEKit does not access the websites you visit.