Each Ultimity browser release is built from Mozilla's source for the Firefox version shown, under the Mozilla Public License 2.0, with the Ultimity overlay applied. Both are below. Ultimity does not change Mozilla's files.
| Release | Firefox | Firefox source | Ultimity overlay |
|---|---|---|---|
| 2026.9.25.1 | 153.3.0 | Mozilla source | Ultimity overlay · manifest |
| 2026.9.24.2 | 153.3.0 | Mozilla source | Ultimity overlay · manifest |