File format resources

The original JPEG standard from 1992. Defines DCT-based lossy compression and the JFIF file format. Still the canonical reference.

The current W3C PNG specification, including chunk definitions, colour space handling, and the alpha-channel model.

Official documentation for WebP's RIFF container, lossy and lossless modes, and animation chunks.

The AOMedia spec for AVIF, defining how AV1-encoded images are wrapped in the HEIF container format.

Current SVG specification covering paths, filters, animation, and accessibility features.

The de facto reference for audio and video conversion. FFmpeg is the open-source toolchain used in nearly every production pipeline that touches media files.

The official spec for H.264 / AVC, the video codec that underpins MP4 video on essentially every device.

The Alliance for Open Media's spec for AV1, the modern royalty-free video codec used in WebM and AVIF.

The FLAC reference, defining the lossless audio compression format and its container structure.

The ID3 metadata specification used for MP3 and other audio formats. Worth knowing if you care about how artist, title, and album art are encoded.

The ISO standard for PDF. The Adobe-published draft is also widely available and is the canonical reference for the format's structure, fonts, and rendering model.

The ECMA-376 standard for Microsoft's Open XML formats. The spec is dense but it's the source of truth for DOCX, XLSX, and PPTX internals.

OASIS's OpenDocument standard, the format used by LibreOffice and Apache OpenOffice. The open alternative to Microsoft's OOXML.

The current EPUB specification covering reflowable and fixed-layout ebooks, accessibility, and packaging.

The closest thing CSV has to a formal spec. Defines the comma-separated values format, escaping rules, and line-ending conventions.

The canonical JSON spec — short, readable, and the definitive reference for JSON syntax.

The current YAML spec. Important if you ever need to debug YAML's notorious type-inference edge cases.

TOML's simple, readable config-file format. The full spec fits on a single page.

The original XML spec from 1998. Verbose but still the canonical reference for XML processing.

The glTF 2.0 spec. Comprehensive coverage of geometry, PBR materials, animations, and the binary GLB format.

OBJ has no formal modern spec, but the Wikipedia article is the de facto reference for the plain-text format and its MTL companion.

Reference for both ASCII and binary STL — the universal 3D printing format.

Pixar's open-source scene description framework, the foundation for USDZ (Apple's AR format). Increasingly relevant for film and AR pipelines.

Mozilla's reference on image formats supported in browsers — coverage, when to use each, and browser compatibility tables.

Practical guide to web video codecs (H.264, H.265, VP9, AV1) and which container formats they fit into.

Reference for the WebVTT subtitle format used by HTML5 video.

Browser compatibility tables for every web-relevant file format. The reference for “is AVIF supported in Safari yet?”-class questions.

The Swiss Army knife of audio and video conversion. Command-line, free, open-source, and used in essentially every production media pipeline.

Command-line image conversion and manipulation. Handles essentially every image format in existence and supports complex batch processing.

A faster, lower-memory alternative to ImageMagick for image processing. The engine behind sharp, the most popular Node.js image library.

Open-source office suite that doubles as a powerful command-line document converter. Can convert between essentially every office format.

Universal document converter — Markdown to anything, anything to anything. The right tool for converting between text-based formats.

Free ebook management and conversion. The standard tool for converting between EPUB, MOBI, AZW3, and other ebook formats.

Open-source OCR engine. The right tool for adding searchable text to scanned PDFs.