Pretranslation

What is pretranslation?

Pretranslation is a feature in Pontoon that allows strings to be translated automatically using a combination of machine translation and translation memory. If pretranslation is enabled for a locale and project, when a new string is added to a project managed through Pontoon:

• It will be translated (pretranslated) using a 100% match from translation memory or, should that not be available, using the Google AutoML Translation engine with a custom model.
• The string will be stored in Pontoon with a special pretranslated status. The pretranslated status can be used in filters within the translation interface, allowing localizers to easily review pretranslated strings, and either approve or reject them.
• The string will also be saved in the repository (e.g. GitHub), and eventually ship in the product.

While this comes with a potential compromise on quality, pretranslation brings the turn-around time to get a first translation to normally under 30 minutes.

Pretranslation uses Google AutoML Translation as its machine translation engine, selected based on reliability, quality of results, and range of supported locales. The engine is fine-tuned by training it on our own existing translation memories, which increases the chances of matching existing style and terminology.

Opt-in guidelines

To request pretranslation for your locale or a specific project, see Requesting pretranslation.

It’s important to note that these are not strict criteria: members of staff will evaluate each request to opt in individually, based on their knowledge of the project and direct experience with the locale.

Criteria for a new locale

• Request needs to come from translators or managers active within the last month (translating or reviewing).
• There is an active manager for the locale (last activity within 2 months).

Criteria for a new project

• Less than 400 missing strings, except for projects or locales where existing pretranslation statistics provide high confidence.
• Average review time for pretranslations in existing projects is less than 3 weeks.

Criteria for disabling pretranslation

• Approval rate drops below 40%.
• Average review time for pretranslations is longer than 6 weeks.

Note that disabling a project would always involve a conversation with reviewers for the locale.

Monitoring quality and time to review

When pretranslation is enabled and actively used, the Insights tab on a locale page (e.g. https://pontoon.mozilla.org/fr/) or a localization page (e.g. https://pontoon.mozilla.org/fr/firefox) includes a Pretranslation quality chart with monthly data:

• Approved: number of pretranslated strings approved as-is.
• Rejected: number of pretranslated strings rejected.
• Approval rate: percentage of pretranslated strings accepted.
• New pretranslations: total number of strings pretranslated that month.
• chrF++ score: an automatic quality metric computed on rejected strings — the closer to 100, the better. A high score means the rejected strings were close to correct and only needed minor edits.

The same Insights tab also includes a Time to review pretranslations chart, showing two lines of monthly data:

• Average time that month: average number of days between a string being pretranslated and it being reviewed that month.
• 12-month average: rolling average of review time over the 12 months up to that month, useful for identifying longer-term trends.