Newest Extensions


Abstract Theme Carole Pepper

An abstract Firefox theme of the charactor Carole Pepper of Honkai Impact 3rd. Inspired by the color of the character's default skin, including the character's skin tone and clothing color. The copyright owner of the charactor Carole is Mihoyo.

Rated 5 out of 5 stars (1)
31 users
Added Sept. 19, 2023

Jens Theme

Just a theme to enjoy in Thunderbird

Rated 4 out of 5 stars (2)
5 users
Added Sept. 3, 2023

Dark Wood Bird

Un thème bois sombre avec logo Thunderbird

Rated 5 out of 5 stars (1)
66 users
Added Sept. 3, 2023


Synthwave Gradient for Thunderbird Email

Not yet rated
78 users
Added Aug. 29, 2023

Dark electric violet

Dark and violet theme for Thunderbird by Stonymontana

Not yet rated
61 users
Added Aug. 28, 2023


Summersmile adds a lively flair to Thunderbird with a sunny yellow background, playful smiley graphics, and a "sunshine and smiles" theme that refreshes your email experience.

Not yet rated
16 users
Added Aug. 22, 2023

Valorant Red

A Thunderbird theme version with custom 'Valorant'-red CSS

Not yet rated
27 users
Added Aug. 16, 2023

theme kian

best for your tool bars

Not yet rated
41 users
Added Aug. 15, 2023

Real System Theme

Theme that really follows system colors for Thunderbird 115+.

If you get strange colors instead of what you expect: First switch to the built in system theme, then switch to this theme again.

Rated 4 out of 5 stars (4)
110 users
Added Aug. 4, 2023


Extended Version for Ultrawide Monitors

Not yet rated
10 users
Added July 24, 2023

Rose Pine Dawn

A theme based on the Rose Pine Dawn color scheme (

Not yet rated
54 users
Added July 23, 2023


Dark Theme CR style Win11 for New Thunderbird 15.

Rated 2 out of 5 stars (1)
12 users
Added July 19, 2023

Shirasu Azusa Theme

Adds theme of Shirasu Azusa from game called Blue Archive.

Anime, Blue Archive, Cute, Dark, Game, Shirasu Azusa

Not yet rated
12 users
Added July 18, 2023

New Dark Bird

A Thunderbird theme with the new Thunderbird Logo.

Not yet rated
263 users
Added July 18, 2023

Tiger eyes turquoise (light theme alt)

A light theme of a gray toned tiger with turquoise eyes.

This is a modified version of the theme "tiger eyes light blue" from AmSumz.

Not yet rated
83 users
Added July 12, 2023



Not yet rated
13 users
Added June 28, 2023

Muted Sage Gruvbox Dark

Muted Sage Gruvbox dark theme for Thunderbird.
Forked from calvinchd's gruvbox dark theme.

Not yet rated
94 users
Added May 10, 2023


A faithful port of the original Cobalt2 theme by Wes Bos.

Rated 5 out of 5 stars (1)
99 users
Added April 5, 2023

Endless Stars

My first Endless Stars Thunderbird Theme with Twinkling Stars. The only thing missing is the falling star animation.

Rated 5 out of 5 stars (4)
192 users
Added Feb. 11, 2023

SpaceShaman Dark

Step into the dark side of the force and discover the secrets of the cosmos without the risk of eye damage!

Not yet rated
37 users
Added Feb. 2, 2023