Base64 Encode / Decode

Base64 is an encoding that represents binary data (images, files, cryptographic keys) using only printable ASCII characters (A-Z, a-z, 0-9, +, /). It's not encryption — any Base64 can be trivially decoded back to the original bytes. The purpose is transport-safety: getting binary data through channels that only accept text.

Where Base64 shows up daily:

• Data URIs — data:image/png;base64,iVBORw0KGg... embeds an image directly in HTML/CSS without a separate request.
• HTTP Basic Auth — Authorization: Basic <base64(user:password)>.
• JWT tokens — each of the three sections is Base64URL-encoded JSON.
• Email attachments — MIME encodes binary attachments as Base64 so they survive SMTP (which is 7-bit text-only by design).
• PEM certificates / SSH keys — Base64-wrapped DER binary between BEGIN/END headers.
• Browser Blob / FileReader APIs — reading a File as Base64 data URL.
• Config embedding — Kubernetes secrets, GitHub Actions secrets are Base64-encoded for safety in YAML.

Base64 expands output by ~33% (4 output bytes per 3 input bytes, plus padding). Never use it for compression. Never use it as security — anyone can decode.

Standard Base64 uses + and / in its alphabet — which have special meaning in URLs (+ means space, / is a path separator). Base64URL swaps those for - and _, and omits the = padding.

Our tool detects and handles both. If you paste a JWT section (three dot-separated parts), it's Base64URL — decoder autodetects.

# Python (standard library)
import base64
base64.b64encode(b"Hello World").decode()        # "SGVsbG8gV29ybGQ="
base64.b64decode("SGVsbG8gV29ybGQ=").decode()    # "Hello World"
base64.urlsafe_b64encode(b"Hello World").decode()  # Base64URL

// JavaScript (browser + Node)
btoa("Hello World")                        // "SGVsbG8gV29ybGQ="
atob("SGVsbG8gV29ybGQ=")                   // "Hello World"
// ⚠ btoa/atob don't handle Unicode directly — use TextEncoder first:
btoa(String.fromCharCode(...new TextEncoder().encode("héllo")))

// Java 8+
Base64.getEncoder().encodeToString("Hello".getBytes());
Base64.getDecoder().decode(encoded);
Base64.getUrlEncoder().withoutPadding().encodeToString(...);

// Go
import "encoding/base64"
base64.StdEncoding.EncodeToString([]byte("Hello"))
base64.RawURLEncoding.EncodeToString(...)      // no padding

// C#
System.Convert.ToBase64String(Encoding.UTF8.GetBytes("Hello"));
System.Convert.FromBase64String(encoded);

Converting a PDF / image / any binary file to Base64 happens the same way — read the file as bytes, encode, done. The result is a plain string you can embed in JSON, paste into a config file, or drop into an email body.