base62

README

base62

Custom Base-62 Encoder

This repository contains the version of my encoder/decoder for Base-62 in three languages:

• Golang;
• Python;
• TypeScript.

The latter could be downloaded from its NPM repo: https://www.npmjs.com/package/base62-ts.

Motivation

I needed an efficient way to apply a Base-62 encoding/decoding algorithm working the same way in TypeScript/Javascript, Python and Golang environments.

WARNING: Decoding any wrongful string returns an error and 0. You shouldn't use the latter.

Usage

Both versions use the same following dictionary:

Value	Character	Value	Character	Value	Character	Value	Character	Value	Character
0	0	13	d	26	q	39	D	52	Q
1	1	14	e	27	r	40	E	53	R
2	2	15	f	28	s	41	F	54	S
3	3	16	g	29	t	42	G	55	T
4	4	17	h	30	u	43	H	56	U
5	5	18	i	31	v	44	I	57	V
6	6	19	j	32	w	45	J	58	W
7	7	20	k	33	x	46	K	59	X
8	8	21	l	34	y	47	L	60	Y
9	9	22	m	35	z	48	M	61	Z
10	a	23	n	36	A	49	N
11	b	24	o	37	B	50	O
12	c	25	p	38	C	51	P

In other words, they use the following base: 0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ.

For TypeScript:

npm i base62-ts

import * as base62 from 'base62-ts'

const value = 18969

const encoded = base62.encode(value)

// 4VX
console.log(encoded)

const decoded = base62.decode(encoded)

console.assert(value === decoded)

console.assert(base62.isValid("4VX"))

For Go:

go get github.com/cyrildever/base62

import "github.com/cyrildever/base62"

value := "4VX"

decoded, err := base62.Decode(value)

// 18969
fmt.Println(decoded)

encoded, err := base62.Encode(decoded)

assert.Equal(t, value, encoded)

assert.Assert(t, base62.IsValid("4VX"))

For Python:

pip install base62-py

from base62 import decode, encode, is_valid_base62

value = 18969

encoded = encode(value)

# 4VX
print(encoded)

decoded = decode(encoded)

assert value == decoded

assert is_valid_base62(encoded)

License

All versions are available under a MIT license (see LICENSE).

---

© 2021-2026 Cyril Dever. All rights reserved.

Documentation

Index

• func Decode(value string) (uint, error)
• func Encode(value uint) (string, error)
• func IsValid(input string) bool
• type Base62
  • func ToBase62(value int) Base62
  • func (b Base62) Bytes() []byte
  • func (b Base62) IsEmpty() bool
  • func (b Base62) NonEmpty() bool
  • func (b Base62) String() string
  • func (b Base62) Value() int

Functions

func Decode

func Decode(value string) (uint, error)

Decode ...

func Encode

func Encode(value uint) (string, error)

Encode ...

func IsValid

func IsValid(input string) bool

IsValid ...

Types

type Base62

type Base62 string

Base62 is a base62 string representation of a byte array. NB: if the passed string is not a valid base62 representation, it will not throw an error but rather returns empty or nil items when methods are called.

const ERROR Base62 = Base62("%") // TODO Make more robust

func ToBase62

func ToBase62(value int) Base62

ToBase62 ...

func (Base62) Bytes

func (b Base62) Bytes() []byte

Bytes ...

func (Base62) IsEmpty

func (b Base62) IsEmpty() bool

IsEmpty ...

func (Base62) NonEmpty

func (b Base62) NonEmpty() bool

NonEmpty ...

func (Base62) String

func (b Base62) String() string

String ...

func (Base62) Value

func (b Base62) Value() int

Value returns `-1` if the string is invalid, the actual integer value otherwise