File formats should never break your workflow
OKfmt is a free online file conversion service. 188 tools across image, PDF, subtitle, audio, video, data, spreadsheet, archive, and font categories, 18 interface languages, no ads, no signup, and files are deleted immediately after conversion.
Four non-negotiable boundaries
Conversion only
The service is strictly scoped to format conversion and in-format processing. Background removal, upscaling, and watermark editing are intentionally excluded. A clear boundary means every feature is thoroughly tested and every result is predictable.
Privacy by default
Files are uploaded over HTTPS and deleted from the server immediately after conversion, with no persistent storage of any kind. EXIF shooting parameters and GPS coordinates are stripped from images by default; keeping them is an explicit opt-in.
New formats first
WebP, AVIF, and HEIC are first-class citizens, not afterthoughts. Five-format subtitle conversion (SRT, VTT, ASS, SBV, LRC) plus shift, trim, and bilingual merge workflows are rare capabilities among comparable services.
Free, without ads
Every feature is free, pages carry no advertising, and no account is required. Sustainability comes from architecture: zero server-side storage, client-side ZIP packaging, and strictly bounded bandwidth and compute costs.
188 tools, nine format categories
WebP / AVIF / HEIC / JPG / PNG / GIF / SVG / ICO / TIFF / BMP
Image formats: conversion among WebP, AVIF, HEIC, JPG, PNG, GIF, SVG, ICO, TIFF, and BMP; same-format compression for JPG/PNG/WebP/AVIF/SVG; original-format resizing; full favicon deployment package generation.
PDF / DOCX / ODT / RTF / EPUB
PDF and documents: merge images into a single PDF, render PDF pages to images at 96/144/300 DPI, merge or split PDF pages, and extract text from PDF, DOCX, ODT, RTF, and EPUB files.
SRT / VTT / ASS / SBV / LRC
Subtitles: conversion among SRT, VTT, ASS, SBV, and LRC plus plain-text export; shift, trim, and bilingual merge workflows; automatic encoding detection covering GBK, Big5, Shift_JIS, and other legacy encodings.
MP3 / WAV / FLAC / OGG / M4A / AAC / OPUS
Audio: convert between MP3, WAV, FLAC, OGG, M4A, AAC, and OPUS with adjustable bitrate, sample rate, and channels; extract audio tracks from video files.
MP4 / WebM / MOV / MKV / AVI / GIF
Video: convert between MP4, WebM, MOV, MKV, AVI, and GIF with quality-based CRF encoding, including legacy recorder and surveillance containers.
JSON / CSV / YAML / XML / TOML
Data: convert structured data between JSON, CSV, YAML, XML, and TOML with scalar types and document structure preserved.
XLSX / XLS / ODS / CSV / JSON
Spreadsheets: convert between XLSX, XLS, ODS, CSV, and JSON; formulas export as their cached values.
ZIP / 7Z / TAR / TGZ / RAR / ISO
Archives: repack between ZIP, 7Z, TAR, and TGZ; unpack RAR, ISO, CAB, DEB, and RPM into ZIP.
TTF / OTF / WOFF2
Fonts: convert between TTF, OTF, and WOFF2 with Brotli compression for smaller web delivery.