Dev Tools

A REST client in a tab: build the request, press Send, and when a call gets blocked, read the CORS reason in words plus a server snippet.

Base64 encode text or decode it back, UTF-8 clean, so emoji and accented letters survive the round trip. Files go in too, with an optional data: URI wrapper.

Hash a password with bcrypt at any cost factor from 4 to 31, or paste an existing $2a$, $2b$ or $2y$ hash and check a password against it. The cost and salt are read out of the hash.

Paste a cron expression and read it back in plain English, column by column, with the next five run times in UTC, your own zone or the server's.

A CSV viewer that reads the delimiter off the file and shows its working, types every column so prices sort by value, and downloads the filtered view under the file's own name.

Convert a curl command to code for 30 targets, including seven separate Node.js HTTP clients.

Encrypt a file behind a password with AES-256-GCM and get back a .tray you can open on any machine. The key is stretched with PBKDF2 at 600,000 iterations.

Hash generator for MD5, SHA-1, SHA-256, SHA-384, SHA-512 and CRC32, plus keyed HMAC and a compare box that says outright whether two checksums match.

Convert HTML to Markdown, or render Markdown back to HTML, with the result redrawing as you type. Turndown handles one direction, markdown-it the other, and GFM tables survive both.

An HTML entity encoder and decoder in one box: escape & < > " and ', or fold entities back into plain characters.

Convert an image to Base64 and copy it four ways: the data URI, a ready-made <img> tag, a background-image rule, or the bare payload. PNG, JPEG, GIF, WebP and SVG all encode.

A JSON diff that parses both sides before it compares them, so reordered keys count for nothing and every real change arrives as a key path like items[2].price.

A JSON formatter with a validator attached: indent at 2 or 4 spaces, minify to one line, or fold a huge payload into a tree.

Turn a JSON sample into TypeScript interfaces, or switch the output to Go structs with json tags, Zod schemas, or Pydantic models. Name the root type and the nested ones follow it.

A JWT decoder that splits a token into its three segments, turns iat and exp into readable UTC times, and checks the signature against a secret or public key you paste.

A Markdown table generator for CSV or spreadsheet rows. Paste them in, the first line becomes the header, and the output is padded so columns line up in the raw text too.

Markdown to HTML with the rendered page beside the source. Pipe tables, 36 highlighted languages, Mermaid diagrams, and a markdown.html download.

A meta tag generator for link previews: nine fields in, up to fifteen lines of head markup out, with the share card and the search result they make drawn above the fields.

A Parquet viewer that edits as well as reads. Open a .parquet file, walk its schema, page through ten million rows, change a cell, then save real Parquet or export the view as CSV.

A regex tester that reads the pattern back to you in plain English as it highlights every match and group.

Compare two Excel or Google Sheets ranges by pasting them side by side. Changed cells light up, added rows go green, removed rows red.

SQL playground running a real SQLite engine: query a sample schema or open your own .sqlite file, then pretty-print the query in any of eleven dialects.

JSON escape and unescape, plus JavaScript literals, \uXXXX Unicode and backslash sequences. Four modes, both directions.

A subnet calculator for IPv4 and IPv6 that reads a CIDR or an address and mask as you type. Network and broadcast, mask and wildcard, usable host range, plus ip6.arpa and EUI-64 for v6.

A text and code diff checker that goes down to the word: edited lines show only the parts that actually changed, and the comparison exports as a unified .diff.

Turn a Unix timestamp into a readable date or a date back into epoch seconds. Auto-detect sorts 10-digit from 13-digit.

A URL encoder and decoder with the encodeURIComponent versus encodeURI choice made explicit: Component escapes / and & inside a query value, Full URL leaves them standing.

Enter two hex colors and get the WCAG contrast ratio, four pass/fail badges covering AA and AAA at both text sizes, and a live preview at 16px and 24px.

An XML formatter and validator that also converts XML to JSON and back, with errors pinned to the line.