About this tool
File Extension Lookup is a searchable, curated reference of widely used file extensions. Each entry answers the question a searcher actually has: what kind of file this is, which programs open it on Windows, macOS, Linux, iOS, Android, and the web, the canonical MIME type to use in Content-Type or upload validation, the platforms that produce or consume the format, and any security or privacy concerns to know before opening. The dataset covers documents (pdf, docx, doc, rtf, odt, txt, md), spreadsheets (xlsx, xls, csv, tsv, ods), presentations (pptx, ppt, key), e-books (epub, mobi, azw3), images (png, jpg, jpeg, webp, avif, heic, gif, bmp, tiff, ico, svg, psd, ai, raw, dng), video (mp4, mov, mkv, webm, avi), audio (mp3, aac, wav, flac, ogg, opus), archives (zip, rar, 7z, tar, gz), disk images (iso, dmg, img), executables and installers (exe, msi, dll, app, pkg, deb, rpm, apk, ipa), fonts (ttf, otf, woff, woff2), web and source code (html, css, js, ts), data and config (json, yaml, xml, toml, ini, env, log, jsonl, rss), databases (sql, sqlite), subtitles (srt, vtt), CAD and 3D (stl, obj), scripts (sh, ps1, bat), and shortcuts (torrent, url, lnk). Type a few characters of an extension (heic, ipa, env) and the matching card loads with platforms, programs, MIME type, a plain-language explanation, and a security note when the format has known risks. Three copy buttons grab the bare extension, the MIME type, or a copy-friendly summary block. A category filter narrows the browse list to documents, archives, video, executables, and so on, and a risk filter surfaces the formats that need a security review before opening. Everything runs in your browser; nothing you type is sent anywhere.
Free to use. Works in your browser. No signup, no login.