Base64 encoding and decodingBaseline · Widely available
The atob() and btoa() global functions encode and decode strings to and from base 64, respectively.
Supported in all major browsers for at least 30 months — safe to use without fallbacks. Baseline since Sep 20, 2016. Widely available since Mar 20, 2019.
Browser support
DesktopChrome
1–29Not supported
30+Supportedsince Oct 1, 2013
Current: 155Edge
12+Supportedsince Jul 29, 2015
Current: 154Firefox
1–3.6Not supported
4+Supportedsince Mar 22, 2011
Current: 157Safari
1–9.1Not supported
10+Supportedsince Sep 20, 2016
Current: 27MobileChrome Android
18–29Not supported
30+Supportedsince Oct 2, 2013
Current: 155Firefox Android
4+Supportedsince Mar 29, 2011
Current: 157Safari iOS
1–9.3Not supported
10+Supportedsince Sep 13, 2016
Current: 27How to use
This feature is Baseline widely available — use it freely, no fallback needed.
Example
Full syntax and examples are on MDN: atob.
Feature detection
JS · check before using
if ("atob" in globalThis) {
// atob is available
} else {
// load a polyfill or use a fallback
}Specification
Usage share
Sub-features
Support for each part of the feature (4). The overall table above shows when the whole feature works.