Base64 vs URL Encoding — Key Differences Explained
Both Base64 and URL encoding (percent-encoding) convert data into a safe text format — but they solve very different problems and produce very different output. Confusing the two is a common source of bugs. This guide explains each one, when to use it, and how the output compares.
The core difference
- Base64 — converts binary data (bytes) into a fixed 64-character alphabet (A–Z, a–z, 0–9, +, /). Used to safely represent binary data as text.
- URL encoding (percent-encoding) — encodes characters that have special meaning in a URL (like
&,=, spaces) so they are treated as literal data. Used to make text safe for inclusion in a URL.
Side-by-side comparison
| Property | Base64 | URL Encoding |
|---|---|---|
| Purpose | Binary data → text | Text → URL-safe text |
| Output characters | A–Z a–z 0–9 + / = | Original + %XX sequences |
| Size increase | ~33% | Varies (1–3x for special chars) |
| Reversible | Yes | Yes |
| Works in URLs | Partially (+ and / clash) | Yes — that is the point |
| Handles binary | Yes | No (text only) |
| JS encode fn | btoa() / Buffer.from() | encodeURIComponent() |
| JS decode fn | atob() / Buffer.from() | decodeURIComponent() |
Encoding the same string — output comparison
const input = 'hello world & price=₹500';
// Base64
btoa(input);
// Error! btoa() can't handle ₹ (multi-byte)
// Correct approach:
Buffer.from(input).toString('base64');
// → 'aGVsbG8gd29ybGQgJiBwcmljZT3igrQ1MDA='
// URL encoding
encodeURIComponent(input);
// → 'hello%20world%20%26%20price%3D%E2%82%B9500'When to use Base64
- Embedding images, fonts, or files as inline data URIs in HTML/CSS
- Encoding binary file content for inclusion in a JSON field
- HTTP Basic Authentication credentials
- The payload and header sections of a JWT token
- Email MIME attachments
When to use URL encoding
- Encoding user search input for a query string parameter
- Including a redirect URL as a query parameter
- Encoding form data submitted via
application/x-www-form-urlencoded - Making REST API parameters with spaces or special characters safe
- Encoding non-ASCII filenames in Content-Disposition headers
URL-safe Base64 — bridging the gap
When you need Base64 inside a URL (e.g., in a JWT), use URL-safe Base64 which replaces + → - and / → _ and removes padding = signs. This avoids conflicts with URL-structural characters while keeping the Base64 encoding scheme.
Try both tools in your browser
Use our Base64 Encoder / Decoder or URL Encoder / Decoder to test encoding instantly — both tools run entirely in your browser with no data uploaded.