A Blob URL (also called an Object URL) is a temporary, browser-generated URL that points to a Blob (Binary Large Object) or File object in memory. It uses the blob: protocol prefix (e.g., blob:https://example.com/550e8400-e29b-41d4-a716-446655440000). Created via URL.createObjectURL(), these URLs allow you to reference in-memory data as if it were a file — perfect for previewing images before upload, generating downloadable files on the fly, or streaming video/audio without a server.

Data URLs (e.g., data:image/png;base64,iVBORw...) embed the complete file content directly in the URL string, making them long and memory-heavy when used repeatedly. Blob URLs are lightweight references to data stored separately in browser memory — they're shorter, faster to create, and don't duplicate data. Blob URLs are also more secure: they're origin-scoped and can be revoked. Data URLs work everywhere; Blob URLs only work within the same browser session and origin.

Use Blob URLs when you need to:
• Preview files before uploading (images, videos, PDFs)
• Generate downloadable content dynamically (export JSON, CSV, text files)
• Display in-memory media without hitting a server
• Create temporary file references for web workers or iframes
• Stream video/audio from MediaRecorder or canvas captures
They're ideal for single-page applications where data lives only in the browser.

No. Blob URLs are strictly temporary and exist only within the current browser session. They will stop working if:
• You call URL.revokeObjectURL() to manually release them
• The page is refreshed or navigated away
• The browser tab is closed
• The document that created them is unloaded
Always revoke Blob URLs when you're done with them to free browser memory. This tool includes a "Revoke" button for each generated URL.

Revoke a Blob URL by calling URL.revokeObjectURL(blobUrl). This removes the mapping between the URL and the underlying Blob data, allowing the browser to garbage-collect the memory. Why it matters: Blob URLs persist in memory until revoked or the page is unloaded. If you create many Blob URLs (e.g., in a loop or over time) without revoking them, you can cause memory leaks that degrade performance. This tool helps you manage that — each generated URL has its own Revoke button, plus a "Revoke All" bulk action.

No. Blob URLs are scoped to the origin (domain + protocol + port) and browser session that created them. If you copy a blob:https://yoursite.com/... URL and send it to someone else, it will not work in their browser — their browser has no Blob data mapped to that URL. For sharing, convert the Blob to a Data URL or upload it to a server.

Any valid MIME type can be used. Common ones include:
• text/plain — plain text files
• text/html — HTML documents
• application/json — JSON data
• text/csv — CSV spreadsheets
• image/png, image/jpeg, image/webp — images
• audio/mpeg, video/mp4 — media files
• application/pdf — PDF documents
• application/octet-stream — generic binary data
This tool provides a preset list and also accepts custom MIME types.

Yes, Blob URLs are safe by design. They are origin-scoped, meaning a Blob URL created on https://yoursite.com cannot be accessed by scripts running on other domains. They also don't expose data in the URL string itself (unlike Data URLs). However, be mindful that Blob URLs can be used for phishing if an attacker generates a malicious HTML Blob and tricks users into opening it — treat Blob URLs with the same caution as any other URL from untrusted sources.

Blob URLs last until the document is unloaded or URL.revokeObjectURL() is called. There's no built-in expiration time. In practice, this means they survive across the lifetime of the page — you can navigate within a single-page app and the Blob URL remains valid. But a full page refresh or tab close will invalidate all Blob URLs created by that document.

Blob URLs (URL.createObjectURL) are supported in all modern browsers: Chrome 23+, Firefox 19+, Safari 6.1+, Edge 12+, and Opera 15+. Internet Explorer 10+ also supports them with the msSaveOrOpenBlob prefix. For mobile, iOS Safari 6.1+ and Android Chrome all support Blob URLs. The blob: protocol is a well-established web standard (part of the File API specification).