Custom Base64 Alphabet Mapper

Alphabet (64 chars)
Standard padding
Custom padding
Standard Base64
Length: 0
Custom Base64
Length: 0

How custom Base mapping works

  • Alphabet: choose any 64 unique characters as the Base64 alphabet (standard is A–Z, a–z, 0–9, +, /).
  • Remapping: this tool remaps characters from the source alphabet to the target alphabet 1‑to‑1, without re‑encoding the payload.
  • Padding: = can be kept, changed to another symbol, or removed entirely; both sides must agree.
  • Compatibility: custom alphabets are not interoperable with standard Base64 unless the receiver knows your alphabet and padding rules.
  • Safety: this is a textual substitution layer over Base64; it does not add encryption or integrity by itself.

How to Use

What this tool does

Remap between standard Base64 and a custom 64‑character alphabet (with optional custom padding). This is a 1‑to‑1 character substitution over Base64—no re‑encoding.

Steps

  1. Enter a 64‑character alphabet (unique chars) and choose padding behavior.
  2. Paste standard Base64 on the left or custom Base64 on the right.
  3. Click “Std → Custom” or “Custom → Std” to map across; copy as needed.

Examples

Notes