mozilla/experimenter

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A web application for managing user experiments for Mozilla Firefox.

Stars: 151
Forks: 229
Open beginner issues: 13
Indexed issues: 409
Avg merge: 1d 8h
Merged PRs (30d): 212

Dominant language: Python
License: MPL-2.0
Last GitHub push: Sep 18, 2026
Latest indexed: Sep 19, 2026
Contributing guide: Contributing guide
Code of conduct: Code of conduct
Beginner labels: No beginner labels indexed

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409 open issues indexed

Remove deprecated New Tab addon version targeting configs Open

Difficulty 3/5 1-2 days Newbie friendliness 65/100

mozilla/experimenter#17358 · Opened Sep 17, 2026
Add version-stripped New Tab targeting configs Open

Difficulty 3/5 1-2 days Newbie friendliness 62/100

mozilla/experimenter#17357 · Opened Sep 17, 2026
Remove the allowedNotificationOrigins PRESERVED_TARGETING_KEYS stopgap once the manifest records it Open

mozilla/experimenter#17342 · 1 assignee · Opened Sep 16, 2026
Map allowedNotificationOrigins to its BigQuery column in jexl_to_sql Open

mozilla/experimenter#17338 · 1 assignee · Opened Sep 16, 2026
Auto inject the control trigger empty message for exposure events Open

Difficulty 3/5 1-2 days Newbie friendliness 55/100

mozilla/experimenter#17303 · Opened Sep 15, 2026
Targeting criteria request Open

Difficulty 5/5 Over a week Newbie friendliness 30/100

mozilla/experimenter#17273 · Opened Sep 11, 2026
[Rollout UI] Documentation link title errors are hidden for every link, not just newly added ones Open

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

mozilla/experimenter#17258 · Opened Sep 10, 2026
Warn when a desktop delivery uses deprecated fxms-message-N placeholder features Open

mozilla/experimenter#17149 · 1 assignee · Opened Sep 4, 2026
Fail CI on feature manifest errors Open

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

mozilla/experimenter#17133 · 1 comment · Opened Sep 3, 2026
Isolate integration test Kinto concurrency by splitting nimbus_ui into single-worker jobs Open

mozilla/experimenter#17132 · 1 assignee · Opened Sep 3, 2026
STMO Link for Popsize query returns individual client rows instead of counts Open

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

mozilla/experimenter#17119 · Opened Sep 2, 2026
Warn on missing/mismatched desktop message triggers across branches Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

mozilla/experimenter#17099 · 1 comment · Opened Sep 1, 2026
[Rollout UI] "Preview with about:messagepreview" button missing on the new UI Open

Difficulty 3/5 1-2 days Newbie friendliness 55/100

mozilla/experimenter#17027 · Opened Aug 27, 2026
Warn about population estimates that do not have version coverage Open

Difficulty 3/5 1-2 days Newbie friendliness 48/100

mozilla/experimenter#16991 · Opened Aug 25, 2026
test_release_date_for_first_run_experiment fails intermittently when a run crosses midnight UTC Open

mozilla/experimenter#16977 · 1 assignee · Opened Aug 25, 2026
Message "lane" visualization Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

mozilla/experimenter#16976 · Opened Aug 25, 2026
Add message collision detection into Experimenter Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

mozilla/experimenter#16975 · 1 comment · Opened Aug 25, 2026
Encode bucket-config value validation in schema Open

Difficulty 3/5 1-2 days Newbie friendliness 42/100

mozilla/experimenter#16972 · Opened Aug 25, 2026
Set max ratio in schema Open

Difficulty 3/5 1-2 days Newbie friendliness 35/100

mozilla/experimenter#16970 · Opened Aug 25, 2026
[Rollout UI] Existing rollouts without a rollout schedule cannot be disabled Open

Difficulty 3/5 1-2 days Newbie friendliness 64/100

mozilla/experimenter#16964 · 1 comment · Opened Aug 25, 2026
Remove featureValidationOptOut from Experimenter Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

mozilla/experimenter#16948 · Opened Aug 24, 2026
Remove featureValidationOptOut from schemas Open

Difficulty 3/5 1-2 days Newbie friendliness 52/100

mozilla/experimenter#16947 · Opened Aug 24, 2026
Set a reasonable maximum for the ratio field Open

Difficulty 2/5 1-3 hours Newbie friendliness 55/100

mozilla/experimenter#16862 · Opened Aug 19, 2026
Migration from old to new rollouts phases Open

Difficulty 3/5 1-2 days Newbie friendliness 58/100

mozilla/experimenter#16825 · Opened Aug 17, 2026
faker providers are loaded in the migrate job Open

Difficulty 3/5 1-2 days Newbie friendliness 55/100

mozilla/experimenter#16769 · Opened Aug 13, 2026
Try out cache mounts for yarn, uv, etc commands Open

Difficulty 3/5 1-2 days Newbie friendliness 55/100

mozilla/experimenter#16764 · Opened Aug 13, 2026
Fix rollouts header not updating when form changes are made Open

mozilla/experimenter#16751 · 1 assignee · Opened Aug 12, 2026
feature selector list closes when adding / removing a feature Open

Difficulty 3/5 1-2 days Newbie friendliness 55/100

mozilla/experimenter#16724 · Opened Aug 11, 2026
Sort selected features to top of list in feature config selector on branch page Open

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

mozilla/experimenter#16723 · Opened Aug 11, 2026
Break up experiments/constants.py Open

Difficulty 5/5 Over a week Newbie friendliness 28/100

mozilla/experimenter#16722 · Opened Aug 11, 2026
Cancelling "request launch without preview" yields cryptic error Open

Difficulty 3/5 1-2 days Newbie friendliness 55/100

mozilla/experimenter#16643 · Opened Aug 5, 2026
Add a workflow for the message consult approval Open

mozilla/experimenter#16641 · 1 assignee · Opened Aug 5, 2026
Cirrus returning different feature sets for the same client Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

mozilla/experimenter#16634 · 1 comment · Opened Aug 5, 2026
placeholder experiments for testing generate with invalid fields Open

Difficulty 3/5 1-2 days Newbie friendliness 42/100

mozilla/experimenter#16591 · Opened Jul 31, 2026
Re-write launch controls as django forms Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

mozilla/experimenter#16590 · Opened Jul 31, 2026
Use Django form rendering with custom templates Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

mozilla/experimenter#16589 · Opened Jul 31, 2026
Development server missing some schemas with version=None Open

Difficulty 2/5 1-3 hours Newbie friendliness 65/100

mozilla/experimenter#16586 · Opened Jul 31, 2026
Audit existing targeting constants for firefox messaging task Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

mozilla/experimenter#16571 · Opened Jul 30, 2026
Support Firefox Desktop Background Message task targeting environment Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

mozilla/experimenter#16570 · Opened Jul 30, 2026
Configure manifesttool to support application field Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

mozilla/experimenter#16568 · Opened Jul 30, 2026
Add a separate application entry for the Firefox Messaging task Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

mozilla/experimenter#16567 · Opened Jul 30, 2026
Remove show-errors flag Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

mozilla/experimenter#16556 · Opened Jul 29, 2026
Use UV dependency groups Open

Difficulty 2/5 1-3 hours Newbie friendliness 64/100

mozilla/experimenter#16541 · Opened Jul 28, 2026
Add SQL query button to targeting Open

mozilla/experimenter#16509 · 1 assignee · Opened Jul 27, 2026
Results summary arrow doesn't match overall results Open

Difficulty 3/5 1-2 days Newbie friendliness 58/100

mozilla/experimenter#16473 · Opened Jul 24, 2026
[Targeting] newtab trainhop 154.8.20260716.43450 widgets-any-four-engaged targeting request Open

Difficulty 3/5 1-2 days Newbie friendliness 55/100

mozilla/experimenter#16366 · Opened Jul 17, 2026
Experimenter does not prompt to save when navigating away from pages with unsaved changes Open

Difficulty 3/5 1-2 days Newbie friendliness 55/100

mozilla/experimenter#16343 · Opened Jul 16, 2026
Jetstream data fetch clobbers populated results_data with empty windows on a mid-run read Open

mozilla/experimenter#16311 · 1 assignee · Opened Jul 15, 2026
validate firefoxLabsTitle, firefoxLabsDescription against fluent strings Open

Difficulty 3/5 1-2 days Newbie friendliness 55/100

mozilla/experimenter#16247 · Opened Jul 9, 2026
Use TestCase.assertDictEqual when comparing DRF serializer errors Open

Maintenance Task

Difficulty 2/5 1-3 hours Newbie friendliness 64/100

mozilla/experimenter#16198 · Opened Jul 3, 2026

mozilla/experimenter

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