Converters
Translate between formats without scripting
JSON ↔ YAML ↔ TOML, CSV ↔ JSON, Markdown ↔ HTML, cURL → fetch/axios/Python, image format conversions. Sensible options surfaced; long-tail flags tucked away.
Roman Numeral Converter
Convert between Roman numerals and numbers, both directions. Rejects readable-but-invalid forms like IIII and IM.
Create ZIP
Bundle several files into one .zip, with a compression level you choose. Runs in your browser — nothing is uploaded.
Unzip Archive
Open a .zip, .7z, .rar, .tar or .tar.gz and pull out the files you need. Runs in your browser — the archive is never uploaded.
JSON ↔ YAML ↔ TOML Converter
Convert between JSON, YAML, and TOML. Auto-detect input format. Browser-only.
CSV ↔ JSON Converter
Convert between CSV and JSON. Auto-detect delimiter, quote handling, header row toggle. Browser-only.
Markdown ↔ HTML Converter
Convert Markdown to HTML and back. GFM (tables, task lists) supported. Browser-only.
curl → Code Converter
Convert curl commands to fetch, axios, Node, Python, PHP, Go. Browser-only.
Image Format Converter
Convert images between PNG, JPEG, and WebP in your browser. Quality slider for lossy formats. AVIF input supported (decode). Max 10 MB. 100% local.
IP Subnet Calculator (CIDR)
IPv4 CIDR calculator — network, broadcast, usable host range, netmask, wildcard, binary view, class and private/public detection. 100% local.
Chmod Calculator
Convert Unix file permissions between checkboxes, octal (755) and symbolic (rwxr-xr-x) — setuid/setgid/sticky included, chmod command ready to copy. 100% local.
XLSX to CSV / JSON Converter
Open an .xlsx workbook, pick a sheet, and export it as CSV or JSON. Dates come out as dates, formulas as their results. Runs in your browser.
DOCX to Markdown Converter
Turn a Word .docx into Markdown — headings, bold, lists, links and GFM tables. Clean HTML too. Runs in your browser.
Image to Base64
Turn an image into a base64 data URI ready to paste into HTML, CSS or Markdown — and back again. Runs entirely in your browser.
Protobuf Decoder
Decode a Protocol Buffers payload to JSON — paste a .proto for real field names, or decode blind by wire format alone when you only have the bytes. Browser-only.
MessagePack ↔ JSON
Decode a MessagePack payload to JSON, or encode JSON to MessagePack, with a byte-count comparison. Accepts hex, Base64, or an uploaded .msgpack file. Browser-only.
Font Converter
Convert a TTF/OTF to WOFF (or back), and subset a font down to only the characters you need. Runs in your browser — nothing is uploaded.
Audio Trim
Cut a clip out of an mp3, wav, ogg or m4a on a waveform, listen back, and download the result as a .wav. Runs in your browser — nothing is uploaded.
Choosing between these tools
Most conversions are lossy in one direction and not the other, and knowing which way is the whole skill. CSV to JSON is safe; JSON to CSV throws away nesting. Markdown to HTML is faithful; HTML to Markdown drops any attribute Markdown cannot express. The converters here state what they discard instead of quietly discarding it.
JSON, YAML and TOML describe the same shapes with different rules, so the round trip is where surprises live — YAML will read an unquoted country code as a boolean, and TOML has no null. The curl converter goes the other way, turning a request you already know works into code in your language, which is usually faster than reading the client library's docs.
Chmod and CIDR are here because both are arithmetic people redo from memory and get wrong. The chmod calculator shows the symbolic and octal forms together; the subnet calculator gives the usable host range, and treats /31 and /32 correctly rather than blindly subtracting two.