The Mozilla trademark and distribution policy is the pair of documents that governs how the Mozilla, Firefox, Thunderbird and other Mozilla names and logos may be used: the Mozilla Trademark Guidelines and the Distribution Policy for Mozilla Software.[1][2] They sit alongside the Mozilla Public License, which licenses the code but grants no rights in any Contributor’s trademarks, service marks or logos (rule).[4] Mozilla explains that it strictly enforces its trademark rights so that it can protect users from people who use the marks to commit fraud. As a result, the right to redistribute and modify the software comes with tight restrictions on using the names and logos, including in the binaries Mozilla provides.[5]
For businesses, the trademark policy is where most Mozilla-specific compliance questions arise. It applies when Firefox is bundled with hardware or software, repackaged with changed defaults, rebuilt from source, offered as a hosted service, or named in products and marketing.
Trademarks covered
Mozilla’s Trademarks List names wordmarks and logos including Mozilla, Firefox, Firefox Developer Edition, Firefox Focus, Thunderbird, MDN, Bugzilla and SUMO. It notes that marks missing from the list are not waived.[3] Its sample attribution notices attribute the marks to the Mozilla Foundation, for example that Firefox “is a trademark of the Mozilla Foundation in the U.S. and other countries”.[3]
Uses allowed without permission
The Trademark Guidelines permit, without specific permission:[1]
- using Mozilla wordmarks in text to refer truthfully to, or link to, unmodified Mozilla programs, products, services and technologies;
- using Mozilla logos to refer or link to products and services hosted on Mozilla servers;
- describing a Firefox add-on under the add-on guidelines, for example “NewGadget Extension for Firefox” but not “Firefox NewGadget Extension”;
- stating that software is based on, or compatible with, Mozilla’s open source code, under the Open Source Project Guidelines;
- describing social media accounts under the social media guidelines.
All other uses, including any use of a Mozilla trademark in a domain name, require prior written permission.[1] The general rules require the marks to be used exactly as listed, only as adjectives and with an attribution notice. They must not appear in the name of a business, product, service or domain, must not imply affiliation or endorsement, and must not be displayed more prominently than the user’s own name.[1] Commercial use such as technical support services is prohibited unless it is a truthful, descriptive reference, for example “Independent technical support for Mozilla’s Firefox browser”.[1]
Redistributing unaltered software
The Unaltered Software Distribution Policy allows unaltered copies of Firefox and other Mozilla software from Mozilla.org to be distributed without express permission, subject to rules (program, rule):[2]
| Condition | Requirement |
|---|---|
| Price | No fee, and distribution may not be tied to buying a product or service |
| Personal data | No collection of personal information in the context of the distribution |
| Integrity | Nothing added, removed or changed, including the trademarks, extensions, default settings and search codes |
| Installer | The installation process may not be modified or used to install other themes, plugins, extensions or software |
| Currency | The most recent version must be distributed |
| Android devices | At least 512 MB of RAM, and a means of providing updates if Google Play is not installed |
Mozilla suggests linking to official downloads instead of hosting copies, and reserves the right to change the policy by posting changes.[2] Under the MPL, Mozilla’s own Firefox executables already carry the required source and licence notices.[7] Unaltered redistribution is therefore governed mainly by these trademark conditions.
Modified and rebranded builds
Modified software may be redistributed under the MPL, but not under Mozilla trademarks without prior written consent and, typically, a distribution agreement with Mozilla. The Distribution Policy’s example is that a modified Firefox may not continue to be called Firefox (rule, program).[2] Changes that need permission include, among others:[2]
- changing the default home page or adding bookmarks;
- adding, modifying or deleting source files or installer content;
- changing file locations;
- adding extensions, add-ons or plugins;
- installing themes other than those in the current stable Firefox.
A project that builds on Mozilla code without such an agreement falls under the Open Source Project Guidelines. It must follow the open source licences, choose branding that signals no affiliation with Mozilla, and not use any Mozilla trademark in its user-facing name or branding. The guidelines give “[Something]-fox”, “Moz-[Something]” and “[Something]-zilla” as names to avoid.[1] Such a project may state in words, not logos, that it works with Mozilla software or is based on Mozilla open source technology, but only with an equally prominent statement that it is not officially associated with Mozilla.[1]
Cloud-based services
Services that provide remote access to Mozilla software, such as hosted or isolated browsers, must not use Mozilla trademarks in the service’s name. They may state in words that the service features or provides access to unaltered Mozilla software, for example “[Your Product Name] featuring Mozilla’s Firefox browser” but not “Firefox [Your Product Name]” (rule).[1]
Relationship to the Firefox Terms of Use
The Firefox Terms of Use (effective 2026-09-16) state that Firefox may be used, copied, modified and distributed as long as the open source licences and the Mozilla Trademark Guidelines are followed. They confirm that the Terms give no rights to Mozilla’s copyrights, trademarks or other brand features beyond what they state.[6]
SAM practice
The following practice notes are commentary on the cited documents. Distribution records for Mozilla software should note whether each copy was passed on unaltered (Unaltered Software Distribution Policy), modified under a written agreement, or rebranded without Mozilla marks. Each route has different conditions.[2] Product names, domains and marketing that mention Firefox or Thunderbird should be checked against the general guidelines.[1]
Out of scope
This article does not cover logo artwork and style rules, which the guidelines delegate to Mozilla’s brand sites, trademark registration details by country, or the source-code obligations of the MPL, which are covered in Mozilla Public License 2.0.[1]