Just a Letter is built on open-source work. Every font in the app and on this site is a Google Fonts release under the SIL Open Font License 1.1 or the Apache License 2.0. All are free for commercial use and none requires a paid licence. They are embedded unmodified, except the Playpen Sans and Noto fonts for other alphabets, which ship reduced to the weights the app needs, as their licence permits.
| Font | Licence | Copyright | Designer |
|---|---|---|---|
| Dancing Script Reserved Font Name "Dancing Script" | OFL 1.1 | Copyright 2016 The Dancing Script Project Authors | Pablo Impallari |
| Caveat | OFL 1.1 | Copyright 2014 The Caveat Project Authors | Pablo Impallari |
| Parisienne Reserved Font Name "Parisienne" | OFL 1.1 | Copyright (c) 2012 by Brian J. Bonislawsky DBA Astigmatic (AOETI) | Astigmatic |
| Indie Flower | OFL 1.1 | Copyright 2010 The Indie Flower Authors | Kimberly Geswein |
| Alex Brush | OFL 1.1 | Copyright 2011 The Alex Brush Project Authors | Robert E. Leuschke (TypeSETit) |
| Homemade Apple | Apache 2.0 | Copyright (c) 2010 by Font Diner, Inc. All rights reserved. | Font Diner |
| Gloria Hallelujah | OFL 1.1 | Copyright (c) 2010, Kimberly Geswein | Kimberly Geswein |
A letter in Greek, Cyrillic, Hebrew, Arabic, Thai or Hindi is written in the matching Playpen Sans, a handwriting family with a version for each of these scripts. Cyrillic can also be written in Caveat. Japanese, Korean and Chinese letters use Yomogi, Nanum Pen Script and LXGW WenKai TC, and letters in Bengali, Tamil, Telugu, Georgian, Amharic, Khmer, Burmese and many more use the matching Noto font.
| Font | Licence | Copyright | Designer |
|---|---|---|---|
| Playpen Sans | OFL 1.1 | Copyright 2023 The Playpen Sans Project Authors | TypeTogether |
| Playpen Sans Hebrew | OFL 1.1 | Copyright 2023 The Playpen Sans Project Authors | TypeTogether |
| Playpen Sans Arabic | OFL 1.1 | Copyright 2023 The Playpen Sans Project Authors | TypeTogether |
| Playpen Sans Thai | OFL 1.1 | Copyright 2023 The Playpen Sans Project Authors | TypeTogether |
| Playpen Sans Deva | OFL 1.1 | Copyright 2023 The Playpen Sans Project Authors | TypeTogether |
| Yomogi | OFL 1.1 | Copyright 2020 The Yomogi Project Authors | Satsuyako |
| Nanum Pen Script Reserved Font Name "Nanum, NanumPen" | OFL 1.1 | Copyright (c) 2010, NHN Corporation | Sandoll Communication |
| LXGW WenKai TC | OFL 1.1 | Copyright 2024 The LXGW WenKai Project Authors | LXGW |
| Noto Naskh Arabic | OFL 1.1 | Copyright 2022 The Noto Project Authors | The Noto Project Authors |
| Noto Sans Bengali | OFL 1.1 | Copyright 2025 The Noto Project Authors | The Noto Project Authors |
| Noto Sans Tamil | OFL 1.1 | Copyright 2022 The Noto Project Authors | The Noto Project Authors |
| Noto Sans Telugu | OFL 1.1 | Copyright 2022 The Noto Project Authors | The Noto Project Authors |
| Noto Sans Gujarati | OFL 1.1 | Copyright 2022 The Noto Project Authors | The Noto Project Authors |
| Noto Sans Gurmukhi | OFL 1.1 | Copyright 2022 The Noto Project Authors | The Noto Project Authors |
| Noto Sans Kannada | OFL 1.1 | Copyright 2022 The Noto Project Authors | The Noto Project Authors |
| Noto Sans Malayalam | OFL 1.1 | Copyright 2022 The Noto Project Authors | The Noto Project Authors |
| Noto Sans Oriya | OFL 1.1 | Copyright 2022 The Noto Project Authors | The Noto Project Authors |
| Noto Sans Sinhala | OFL 1.1 | Copyright 2022 The Noto Project Authors | The Noto Project Authors |
| Noto Sans Georgian | OFL 1.1 | Copyright 2022 The Noto Project Authors | The Noto Project Authors |
| Noto Sans Armenian | OFL 1.1 | Copyright 2022 The Noto Project Authors | The Noto Project Authors |
| Noto Sans Ethiopic | OFL 1.1 | Copyright 2022 The Noto Project Authors | The Noto Project Authors |
| Noto Sans Khmer | OFL 1.1 | Copyright 2022 The Noto Project Authors | The Noto Project Authors |
| Noto Sans Lao | OFL 1.1 | Copyright 2022 The Noto Project Authors | The Noto Project Authors |
| Noto Sans Myanmar | OFL 1.1 | Copyright 2022 The Noto Project Authors | The Noto Project Authors |
| Font | Licence | Copyright | Designer |
|---|---|---|---|
| Lora Reserved Font Name "Lora" | OFL 1.1 | Copyright 2011 The Lora Project Authors | Cyreal |
| DM Sans | OFL 1.1 | Copyright 2014 The DM Sans Project Authors | Colophon Foundry, Jonny Pinhorn |
| DM Mono | OFL 1.1 | Copyright 2020 The DM Mono Project Authors | Colophon Foundry |
Eight of the drawing brushes in the app stamp brush tips from the “Deevad 25.01” Krita bundle by David Revoy, released into the public domain under CC0: “You are free to do commercial work with them, to reshare them, to fork them, to reuse them, to include them in your software.” Only the tip images are used; the brushes themselves are built on this app’s own drawing engine. CC0 asks for no credit; he gets it anyway.
The country-flag icons in the site's language switcher are by Magnific, used under Flaticon's free licence:
The app is built with Flutter and a number of open-source Dart packages; the website with Next.js and React. The complete, itemised list of package licences is available in the app under Settings → About → Open-source licences.
SIL Open Font License 1.1 · Apache License 2.0
Thank you to every designer and maintainer who makes their work free to build on.