Licenses & Attribution

1. Content Sources

Sefaria

Torah, Talmud, halachic, and commentary texts are retrieved live from the Sefaria API. Much of the Sefaria corpus is licensed CC-BY or is public domain, but licensing varies by text, and some texts on Sefaria carry more restrictive terms. Sh'elah displays Sefaria content under Sefaria's own terms of use. Verify the license of any specific text on Sefaria before reusing it outside this app. See Sefaria's licensing page for the authoritative, per-text breakdown.

Hebcal

Jewish calendar, holiday, and zmanim (halachic times) data is retrieved from the Hebcal API. Hebcal's own license terms apply to that data; see Hebcal's developer documentation for details.

Wikipedia

Used only as a last-resort general-knowledge source when Judaic texts and computed calendar data cannot answer a question. Wikipedia content is licensed CC-BY-SA, which carries a share-alike obligation. Any downstream reuse of Wikipedia-sourced material retrieved through this app must itself be licensed CC-BY-SA and attributed to Wikipedia. See Wikipedia's reuse guide for the full terms.

Extended to Sh'elah's own AI Output (2026-09-06): this obligation is not limited to a user's own downstream reuse. It also covers Sh'elah's own act of serving an AI Output. Where an AI Output substantially synthesizes retrieved Wikipedia content (the last-resort case described in the AI Disclosure page), that specific answer is treated as CC-BY-SA Adapted Material of the underlying Wikipedia passage: it is attributed to Wikipedia and made available under CC-BY-SA 4.0 for that specific answer. This overrides the general "personal use only" Content license in the Terms of Service §9, which does not apply to this subset of AI Output. This is a deliberately conservative operator choice, adopted 2026-09-06 without a definitive legal determination of whether such synthesis actually creates an "Adapted Material" obligation under CC BY-SA 4.0 §1.1. The choice was made because treating the obligation as applicable carries less risk than assuming it does not.

Halachipedia / HebrewBooks

Whitelisted external halachic sources used as second-tier evidence (after Sefaria and before general web sources). Each carries its own site terms of use; Sh'elah links to and quotes brief excerpts from these sources under fair-use / attribution norms, not a blanket relicense.

2. Fonts

SILEOT

static/fonts/SILEOT.woff / SILEOT.woff2: the font's own name table identifies this as Ezra SIL (also distributed as "SIL Ezra"), a Hebrew biblical OpenType typeface published by SIL International (version 2.51, 2007). Ezra SIL's font software is licensed under the SIL Open Font License (OFL) 1.1, with Reserved Font Names "SIL" and "Ezra"; the OFL permits embedding, use, redistribution, and modification (including in a web/@font-face context) provided the font is not sold on its own and modified versions are renamed away from the reserved names. A separate Hebrew-layout-intelligence component is licensed under the MIT/X11 License (Ralph Hancock and John Hudson).

Cardo and Inter

The text typefaces Cardo and Inter are loaded from Google Fonts. Both are published under the SIL Open Font License 1.1.

3. Open-Source Libraries: Frontend (JavaScript/CSS)

The following libraries are used in the Service's own frontend code and are each MIT-licensed. See each project's own repository for the full license text:

• Tailwind CSS: github.com/tailwindlabs/tailwindcss
• marked: github.com/markedjs/marked
• Motion: github.com/motiondivision/motion
• FullCalendar: github.com/fullcalendar/fullcalendar
• Phosphor Icons: github.com/phosphor-icons/core
• Sentry browser SDK: github.com/getsentry/sentry-javascript

A typical MIT notice (see each project for its exact copyright line):

MIT License

Copyright (c) <year> <copyright holders>

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

DOMPurify (not MIT, dual-licensed)

DOMPurify: github.com/cure53/DOMPurify. DOMPurify is not MIT-licensed. Its own package.json declares "license": "(MPL-2.0 OR Apache-2.0)", meaning a dual license under the Mozilla Public License 2.0 or, at the recipient's option, the Apache License 2.0. Both permit the use made of it here (bundling a minified, unmodified build via CDN into this app); MPL-2.0's file-level copyleft only attaches if DOMPurify's own source files are modified and redistributed, which this project does not do. See DOMPurify's repository for the full license text of both options.

4. Backend (Python) Dependencies

Direct dependencies pinned in requirements.txt. All are permissively licensed (MIT / BSD-3-Clause / Apache-2.0, or a permissive dual choice of those) except one flagged below:

Permissive (MIT / BSD-3-Clause / Apache-2.0): Flask 3.1.3 (BSD-3-Clause), FastAPI 0.141.1 (MIT), Starlette 1.3.1 (BSD-3-Clause), Uvicorn 0.35.0 (BSD-3-Clause), a2wsgi 1.10.10 (MIT), redis 7.4.0 (MIT), python-dotenv 1.2.2 (BSD-3-Clause), requests 2.33.1 (Apache-2.0), httpx 0.28.1 (BSD-3-Clause), pyluach 2.3.0 (MIT), tzdata 2026.2 (Apache-2.0), timezonefinder 8.2.2 (MIT), the Anthropic SDK 0.89.0 (MIT), google-genai 2.23.0 (Apache-2.0), tenacity 9.1.2 (Apache-2.0), PyJWT 2.15.0 (MIT), cryptography 50.0.0 (Apache-2.0 OR BSD-3-Clause, dual), supabase 2.31.0 (MIT), python-docx 1.1.2 (MIT), reportlab 4.2.2 (BSD-style license, per its own license.txt), and sentry-sdk 2.63.0 (MIT).

zmanim 0.3.1 (used in the Service's zmanim/halachic-times calculation engine, backend/zmanim_engine.py) is not a simple permissive license. Its installed package metadata declares the GNU Lesser General Public License v2 or later (LGPLv2+). LGPLv2+ is a "weak copyleft" library license: this project's own code may use the library and remain under its own MIT license (dynamic use/import doesn't trigger the copyleft), but redistributing the zmanim package itself would carry LGPL obligations, including making the LGPL-covered source available and, per LGPLv2 §6, allowing the library to be replaced or relinked with a modified version. No modifications to zmanim's own source are made in this repo.

5. AI Model Providers

Anthropic (Claude) and Google (Gemini) provide the AI synthesis models used by the Service under their respective commercial API terms, not open-source licenses. See our AI Disclosure page for how these are used.