Letterbox
Letterbox is a Firefox browser extension that measures pillarbox or letterbox bars when an image is fitted inside a frame. It is intended for users who need to inspect image framing and aspect-ratio differences in the browser.
Overview
4 featuresIn the Browser DevTools & extensions space, Letterbox takes a focused approach. It focuses on measuring the size of pillarbox or letterbox bars around images fitted inside frames. It is built as a consumer product for firefox users working with image framing and aspect ratios. Letterbox is free to use. Letterbox is available on the web, embeddable surfaces, macOS, Windows, and Linux.
Behind Letterbox is Robert E. Roberts, and it first shipped in 2026. Key capabilities include bar measurement, image framing inspection, and aspect-ratio analysis. The interface is available in 32 languages, including Czech, German, and Greek.
Summary written by a language model from the project’s public pages.
- Bar measurement
- Image framing inspection
- Aspect-ratio analysis
- No data collection
Built with & integrations
Trust & compliance
Indexing history
1What PulseGate has recorded for this listing
Frequently asked questions about Letterbox
- What is Letterbox?
- Letterbox focuses on measuring the size of pillarbox or letterbox bars around images fitted inside frames. It is catalogued under Browser DevTools & extensions on PulseGate.
- Who should use Letterbox?
- Letterbox is a consumer product built for firefox users working with image framing and aspect ratios.
- Does Letterbox have a free plan?
- Yes — Letterbox is free to use.
- What platforms does Letterbox run on?
- Letterbox runs on the web, embeddable surfaces, macOS, Windows, and Linux.
- Is Letterbox still active?
- Unverified. Letterbox has not been re-checked since it entered the index, so there is no finding either way — and only a positive finding would say otherwise.
- What are alternatives to Letterbox?
- Similar projects tracked by PulseGate include Letterboxd Text Formatter, goto letterboxd, and Letterboxd Search.Letterboxd Text Formattergoto letterboxdLetterboxd Search
- Who makes Letterbox?
- Letterbox is developed by Robert E. Roberts.
- How long has Letterbox been around?
- Letterbox first shipped in 2026.
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