Metric Glance converts imperial units and prices inline on pages you visit. All conversion and detection work happens locally in your browser. This policy describes the optional data collection feature that helps improve the detection model.
On first install, a welcome page lets you choose whether to enable data sharing. You can turn this off at any time in Preferences.
Each uploaded record describes one unit or price span that was detected, hovered over, or corrected by you. The following fields are included:
| Field | Description |
|---|---|
| span | The detected text (e.g., "5 miles"). Up to 200 characters. |
| label | The outcome category: "unit", "price", "not_a_conversion", or a correction label you applied. |
| tier | How the record was generated: "corrected" (you corrected it), "seen" (you hovered), or "auto" (detected automatically). |
| num, unit, unit_id | The parsed numeric value and unit identifier (e.g., num=5, unit="miles", unit_id="mi"). |
| before, after | Text immediately before and after the span (up to roughly 500 characters before and 300 characters after, about 800 characters combined). No personally identifying text is targeted, but surrounding words are captured as written on the page. |
| sentence | The sentence containing the span, up to 300 characters. |
| heading | The nearest heading on the page, up to 120 characters. |
| title | The page title, up to 120 characters. |
| url | The hostname of the page only (e.g., "www.example.com"). Never the full URL, path, or query string. |
| lang | The language code declared by the page (e.g., "en"). |
| locale | Your browser's locale setting (e.g., "en-US"). |
| tag | The HTML element type the span appeared in (e.g., "p", "li", "td"). |
| page_units | A list of unit types detected elsewhere on the same page (e.g., ["mi", "lb"]). Up to 40 entries. |
| span_start, span_end | Character offsets of the span within the page's text. |
| interacted | Whether you hovered or clicked the conversion (true/false). |
| seen | Whether the conversion tooltip was shown to you (true/false). |
| ts | Unix timestamp of when the example was logged locally. |
| received_at | The time the server received the record (epoch seconds), recorded on the server. Not read from your device or the page. |
On first install the extension generates a random UUID and stores it in extension storage. This identifier is included with every upload. It is not linked to your browser account, Firefox profile, or any personal information. It is used only to deduplicate incoming records on the server and to enforce a daily upload cap per installation.
Uploaded records are stored in a private database and used to train and evaluate a token-classification model that will replace the extension's current regex-based detection engine. Records are not sold, shared with third parties, or used for advertising.
Records are kept only as long as they are useful for training and evaluating the detection model, and are deleted when they are no longer needed for that purpose.
Turn off "Help improve detection" in extension Preferences at any time; uploads stop immediately. To delete all locally saved examples, click Clear in the "Your corrections" section of Preferences. Records already sent to the server cannot be recalled, as they are not linked to any personal identifier that could be used to find them.
This privacy policy may change over time. If we change what data is collected or how it is used, we will update this page, revise the "Last updated" date above, and the extension version notes will describe the change. The extension also checks this page periodically and shows a notice in your browser when the policy has changed, so you do not have to check back manually. Continued use of the data sharing feature after a change means the updated policy applies; you can turn data sharing off at any time in Preferences.