What characters are valid in base-36?

Base-36 uses digits 0–9 and letters A–Z (case-insensitive). Any other character is invalid and the tool will show an error.

Is this the same as encoding text as base-64?

No. This tool treats the base-36 string as a numeric value and converts the underlying integer to base-64. It does not encode the literal ASCII bytes of the base-36 string.

Can it handle very large numbers?

Yes. The tool uses JavaScript BigInt, which supports arbitrarily large integers with no overflow.

What base-64 alphabet does it use?

The standard RFC 4648 alphabet: A–Z, a–z, 0–9, +, /, with = padding. If you need URL-safe base-64, replace + with - and / with _ in the output.

Is anything sent to a server?

No. All computation happens entirely in your browser. Your data never leaves your device.

Base36 to Base64 Converter

Paste a base-36 string and get the standard RFC 4648 base-64 encoding instantly.

Base-36 Input

Base-36 string (digits 0–9 and A–Z)

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Base-64 Output (RFC 4648)

Enter a base-36 value and click Convert

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Summary

This tool converts a base-36 encoded value (digits 0–9 and letters A–Z, case-insensitive) into its RFC 4648 base-64 representation. The conversion first decodes the base-36 string into its underlying big integer, then re-encodes the raw bytes as base-64. Everything runs client-side in your browser — nothing is sent to a server.

How it works

Enter or paste a base-36 string in the input field.
The tool decodes the string digit-by-digit into a big integer using BigInt arithmetic.
The integer's byte array is extracted in big-endian order.
Those bytes are base-64 encoded per RFC 4648 (standard alphabet, with = padding).
The result appears instantly; click "Copy" to copy it to your clipboard.

Use cases

Convert short-link tokens or ID slugs stored as base-36 into base-64 for storage or transmission.
Debug encoding pipelines that mix base-36 and base-64 representations.
Verify that a base-36 value and a base-64 value encode the same underlying integer.
Explore number-base conversions for educational or cryptographic purposes.
Convert MongoDB or UUID compact IDs between encoding formats.

Frequently Asked Questions

Last updated: 2026-05-28 · Reviewed by Nham Vu