Releases

Current Releases

Standard support

Based on Gecko 147

Firefox 147.0.3
Based on Gecko 147

Released on 2026-02-03

SeaMonkey 2.144
Based on Gecko 147

Released on 2015-03-10

Based on Gecko 31

Thunderbird 60.87.0
Based on Gecko 60

Released on 2026-02-03

Based on Gecko 28

Firefox OS 1.3
Based on Gecko 28

Released on 2014-03-17

Extended support

Based on Gecko 60

Firefox 60.87.0esr
Based on Gecko 60

Released on 2026-01-13

Upcoming Releases

NOTE: The dates listed in this section refer to the date of the code merge, not the date of release. See the branch migration calendar for more information.

Based on Gecko 148

Firefox 148
Based on Gecko 148

Currently in BETA channel
Moves to RELEASE week of February 24, 2026

Thunderbird 148
Based on Gecko 148

Currently in BETA channel

SeaMonkey 2.145
Based on Gecko 148

Currently in BETA channel
Moves to RELEASE week of February 24, 2026

Based on Gecko 54

Firefox 54
Based on Gecko 54

Currently in AURORA channel
Moves to BETA week of February 24, 2026

Thunderbird 54
Based on Gecko 54

Currently in EARLYBIRD channel
Moves to BETA week of February 24, 2026

SeaMonkey 2.51
Based on Gecko 54

Currently in AURORA channel
Moves to BETA week of February 24, 2026

Based on Gecko 149

Firefox 149
Based on Gecko 149

Currently in NIGHTLY channel
Moves to BETA week of February 24, 2026

Thunderbird 149
Based on Gecko 149

Currently in DAILY channel
Moves to BETA week of February 24, 2026

SeaMonkey 2.146
Based on Gecko 149

Currently in NIGHTLY channel
Moves to AURORA week of February 24, 2026

B2G Releases

Firefox OS 1.4
Based on Gecko 30

Released on ??

Firefox OS 2.0
Based on Gecko 32

Currently in BETA channel
Moves to RELEASE week of ??

Firefox OS 2.1
Based on Gecko 34

Currently in AURORA channel
Moves to BETA week of ??

Firefox OS 2.2
Based on Gecko 37

Currently in NIGHTLY channel
Moves to AURORA week of ??

Previous Releases

2015

Release	Date	Notes
SeaMonkey 2.33	March 10	Release Notes
Thunderbird 31.5.0	February 24	Release Notes
SeaMonkey 2.32	January 13	Release Notes
Thunderbird 31.4.0	January 13	Release Notes
Firefox 35.0	January 13	Release Notes

2014 and earlier

For releases prior to 2015, see the archive.

Other Links

This is a page for tracking in-progress releases. For maintenance releases, we use a general checklist to ensure we don't miss anything.

• perhaps you'd like to see who release drivers for various releases are?
• or perhaps you'd like to learn more about the priority rankings we assign to releases?
• you might even wonder how we use flags to manage our releases?
• or what branches exist and when they branched?
• perchance you're confused about update terminology?
• maybe you'd like to know about our various branch support levels?
• perhaps you want to see the RapidRelease Calendar for future aurora merges, beta merges, and releases?
• maybe you are interested in checking the Feature Release Tracker for upcoming features?