About Base64 Encoding
Base64URL Support
Modern applications use JSON Web Tokens (JWT) and URL parameters that require Base64URL encoding (replacing + and / with - and _). This tool automatically detects and normalizes Base64URL safely.
True Binary Extraction
Unlike basic tools that force everything into text, our File Mode processes exact binary buffers. You can paste a Base64 string of an image or PDF and perfectly reconstruct the downloadable file without data corruption.
100% Client-Side Privacy
Your data never leaves your device. Everything from UTF-8 string chunking to Blob extraction processes locally in your browser memory. We never upload files to any server.
Frequently Asked Questions
Is Base64 an encryption method?
Absolutely not. Base64 is merely an encoding scheme designed to translate binary data into a readable ASCII format. Anyone can instantly decode a Base64 string back to its original state. Never use it to hide passwords or secure sensitive data.
Does Base64 increase file size?
Yes. Encoding a file to Base64 generally increases its size by exactly 33% (plus the length of any Data URI prefix). This overhead is why Base64 should only be used to embed small assets — like SVG icons or tiny JPGs — directly into HTML/CSS to save network requests.
Why does my Base64 string fail to decode on other sites?
Many basic tools fail for two reasons: First, they rely on legacy Latin-1 string processing, which destroys Unicode characters (like emojis). Second, they do not support Base64URL character replacements. This tool utilizes native `TextEncoder` and byte-normalization to ensure lossless conversion.
Can I decode Base64 back into an image or PDF?
Yes. Switch to File Mode > Decode Base64 to File. Paste your string, and the tool will extract the raw binary data, identify the file signature, and provide a downloadable file entirely within your browser.