File API
Used by every file upload, image preview, drag-and-drop, and client-side file processing feature. Blob URLs are the bridge between binary data and DOM elements (img, video, a[download]).
What It Defines
Defines the File, Blob, and FileReader interfaces for reading file contents in the browser. Blob provides raw binary data access; File extends Blob with name/lastModified metadata. FileReader provides async methods (readAsText, readAsArrayBuffer, readAsDataURL). Also defines blob: URLs via URL.createObjectURL().
Canonical (Normative)
Convenient (Practical)
Publishes web platform specs including CSS, accessibility, security policies, Service Workers, Web App Manifest, and many browser APIs. Also maintains some versioned HTML/DOM specs.
Related Specs
Streams are how modern browsers handle large data: fetch response bodies, file reads, compression, and encoding are all stream-based. Understanding backpressure and piping is essential for efficient data processing.
The spec behind every HTML page, form, and browser API. The canonical reference for how browsers actually parse and process HTML.