# RecomBuilder

> RecomBuilder is a free web tool that drafts a recommendation letter for the person asking for one to give to their recommender, or for a recommender writing the letter themselves. The standard draft uses a fast AI model (currently Claude Haiku 5.5) at no cost and with no sign-up; for $3, a person can choose one of several leading models from OpenAI, Anthropic, and xAI. All requests use zero-data-retention routing through OpenRouter, and every listed model uses zero data retention. RecomBuilder has no database and does not store answers or letters. A non-personal aggregate draft count persists in App Storage; analytics run only with consent. The site and the letters it writes are available in 25 languages. Made by [Mohammad Keyhani](https://mohammadkeyhani.com/) and DigitVibe Corporation (Canada).

Recommendation letters are also known as letters of recommendation or reference letters.

## Use the tool
- [RecomBuilder home](https://recombuilder.com/index.md): the form, what each field means, and the FAQ
- [Agent API (OpenAPI)](https://recombuilder.com/openapi.json): request a free draft programmatically, with the proof-of-work step explained
- [Current models](https://recombuilder.com/api/models): the free model and today's premium menu, as JSON

## Agent API in brief
1. `GET https://recombuilder.com/api/challenge` returns `{algorithm, challenge, maxnumber, salt, signature}`. Find the integer `n` from 0 to `maxnumber` where the lowercase hex SHA-256 of the string `salt + n` equals `challenge`.
2. Base64-encode the JSON `{"algorithm","challenge","number": n,"salt","signature"}` and send it as `altcha`. Each solution works once and expires in 5 minutes.
3. `POST https://recombuilder.com/api/draft` with JSON: the form fields, optional `role` (`applicant`, the default, or `recommender` when the recommender is filling in the form), `model` (the free model id from /api/models), and `altcha`. Optional `lang` (one of `en`, `es`, `de`, `ja`, `fr`, `pt`, `ru`, `it`, `nl`, `pl`, `tr`, `zh`, `fa`, `vi`, `cs`, `id`, `ko`, `uk`, `hu`, `ar`, `sv`, `ro`, `el`, `da`, `fi`; default `en`) sets the language of the letter, the email, and any error messages. Response: `{ letter_markdown, emailed }`. Premium models require the person to pay in the browser.
4. To revise a letter, send the same fields with optional `revision_request` (up to 2,000 characters of free-form change instructions) and `previous_draft` (up to 40,000 characters of the letter in Markdown). Each revision is a new generation; premium revisions require a new purchase.

## Languages
Every page has a version in each language below, with the same content. English is at the root; other languages use a two-letter prefix. Each Markdown copy is also served from the HTML address with `Accept: text/markdown`.
- English (English, `en`): [https://recombuilder.com/](https://recombuilder.com/) · [Markdown](https://recombuilder.com/index.md) · [Privacy](https://recombuilder.com/privacy.md) · [Terms](https://recombuilder.com/terms.md) · [Accessibility](https://recombuilder.com/accessibility.md)
- Español (Spanish, `es`): [https://recombuilder.com/es/](https://recombuilder.com/es/) · [Markdown](https://recombuilder.com/es/index.md) · [Privacidad](https://recombuilder.com/es/privacy.md) · [Términos](https://recombuilder.com/es/terms.md) · [Accesibilidad](https://recombuilder.com/es/accessibility.md)
- Deutsch (German, `de`): [https://recombuilder.com/de/](https://recombuilder.com/de/) · [Markdown](https://recombuilder.com/de/index.md) · [Datenschutz](https://recombuilder.com/de/privacy.md) · [Nutzungsbedingungen](https://recombuilder.com/de/terms.md) · [Barrierefreiheit](https://recombuilder.com/de/accessibility.md)
- 日本語 (Japanese, `ja`): [https://recombuilder.com/ja/](https://recombuilder.com/ja/) · [Markdown](https://recombuilder.com/ja/index.md) · [プライバシー](https://recombuilder.com/ja/privacy.md) · [利用規約](https://recombuilder.com/ja/terms.md) · [アクセシビリティ](https://recombuilder.com/ja/accessibility.md)
- Français (French, `fr`): [https://recombuilder.com/fr/](https://recombuilder.com/fr/) · [Markdown](https://recombuilder.com/fr/index.md) · [Confidentialité](https://recombuilder.com/fr/privacy.md) · [Conditions](https://recombuilder.com/fr/terms.md) · [Accessibilité](https://recombuilder.com/fr/accessibility.md)
- Português (Brazilian Portuguese, `pt`): [https://recombuilder.com/pt/](https://recombuilder.com/pt/) · [Markdown](https://recombuilder.com/pt/index.md) · [Privacidade](https://recombuilder.com/pt/privacy.md) · [Termos](https://recombuilder.com/pt/terms.md) · [Acessibilidade](https://recombuilder.com/pt/accessibility.md)
- Русский (Russian, `ru`): [https://recombuilder.com/ru/](https://recombuilder.com/ru/) · [Markdown](https://recombuilder.com/ru/index.md) · [Конфиденциальность](https://recombuilder.com/ru/privacy.md) · [Условия](https://recombuilder.com/ru/terms.md) · [Доступность](https://recombuilder.com/ru/accessibility.md)
- Italiano (Italian, `it`): [https://recombuilder.com/it/](https://recombuilder.com/it/) · [Markdown](https://recombuilder.com/it/index.md) · [Privacy](https://recombuilder.com/it/privacy.md) · [Termini](https://recombuilder.com/it/terms.md) · [Accessibilità](https://recombuilder.com/it/accessibility.md)
- Nederlands (Dutch, `nl`): [https://recombuilder.com/nl/](https://recombuilder.com/nl/) · [Markdown](https://recombuilder.com/nl/index.md) · [Privacy](https://recombuilder.com/nl/privacy.md) · [Voorwaarden](https://recombuilder.com/nl/terms.md) · [Toegankelijkheid](https://recombuilder.com/nl/accessibility.md)
- Polski (Polish, `pl`): [https://recombuilder.com/pl/](https://recombuilder.com/pl/) · [Markdown](https://recombuilder.com/pl/index.md) · [Prywatność](https://recombuilder.com/pl/privacy.md) · [Regulamin](https://recombuilder.com/pl/terms.md) · [Dostępność](https://recombuilder.com/pl/accessibility.md)
- Türkçe (Turkish, `tr`): [https://recombuilder.com/tr/](https://recombuilder.com/tr/) · [Markdown](https://recombuilder.com/tr/index.md) · [Gizlilik](https://recombuilder.com/tr/privacy.md) · [Koşullar](https://recombuilder.com/tr/terms.md) · [Erişilebilirlik](https://recombuilder.com/tr/accessibility.md)
- 简体中文 (Simplified Chinese, `zh-Hans`): [https://recombuilder.com/zh/](https://recombuilder.com/zh/) · [Markdown](https://recombuilder.com/zh/index.md) · [隐私](https://recombuilder.com/zh/privacy.md) · [条款](https://recombuilder.com/zh/terms.md) · [无障碍](https://recombuilder.com/zh/accessibility.md)
- فارسی (Persian, `fa`): [https://recombuilder.com/fa/](https://recombuilder.com/fa/) · [Markdown](https://recombuilder.com/fa/index.md) · [حریم خصوصی](https://recombuilder.com/fa/privacy.md) · [شرایط](https://recombuilder.com/fa/terms.md) · [دسترس‌پذیری](https://recombuilder.com/fa/accessibility.md)
- Tiếng Việt (Vietnamese, `vi`): [https://recombuilder.com/vi/](https://recombuilder.com/vi/) · [Markdown](https://recombuilder.com/vi/index.md) · [Quyền riêng tư](https://recombuilder.com/vi/privacy.md) · [Điều khoản](https://recombuilder.com/vi/terms.md) · [Hỗ trợ tiếp cận](https://recombuilder.com/vi/accessibility.md)
- Čeština (Czech, `cs`): [https://recombuilder.com/cs/](https://recombuilder.com/cs/) · [Markdown](https://recombuilder.com/cs/index.md) · [Ochrana soukromí](https://recombuilder.com/cs/privacy.md) · [Podmínky](https://recombuilder.com/cs/terms.md) · [Přístupnost](https://recombuilder.com/cs/accessibility.md)
- Bahasa Indonesia (Indonesian, `id`): [https://recombuilder.com/id/](https://recombuilder.com/id/) · [Markdown](https://recombuilder.com/id/index.md) · [Privasi](https://recombuilder.com/id/privacy.md) · [Ketentuan](https://recombuilder.com/id/terms.md) · [Aksesibilitas](https://recombuilder.com/id/accessibility.md)
- 한국어 (Korean, `ko`): [https://recombuilder.com/ko/](https://recombuilder.com/ko/) · [Markdown](https://recombuilder.com/ko/index.md) · [개인정보 처리방침](https://recombuilder.com/ko/privacy.md) · [이용약관](https://recombuilder.com/ko/terms.md) · [웹 접근성](https://recombuilder.com/ko/accessibility.md)
- Українська (Ukrainian, `uk`): [https://recombuilder.com/uk/](https://recombuilder.com/uk/) · [Markdown](https://recombuilder.com/uk/index.md) · [Конфіденційність](https://recombuilder.com/uk/privacy.md) · [Умови](https://recombuilder.com/uk/terms.md) · [Доступність](https://recombuilder.com/uk/accessibility.md)
- Magyar (Hungarian, `hu`): [https://recombuilder.com/hu/](https://recombuilder.com/hu/) · [Markdown](https://recombuilder.com/hu/index.md) · [Adatvédelem](https://recombuilder.com/hu/privacy.md) · [Feltételek](https://recombuilder.com/hu/terms.md) · [Akadálymentesség](https://recombuilder.com/hu/accessibility.md)
- العربية (Arabic, `ar`): [https://recombuilder.com/ar/](https://recombuilder.com/ar/) · [Markdown](https://recombuilder.com/ar/index.md) · [الخصوصية](https://recombuilder.com/ar/privacy.md) · [الشروط](https://recombuilder.com/ar/terms.md) · [إمكانية الوصول](https://recombuilder.com/ar/accessibility.md)
- Svenska (Swedish, `sv`): [https://recombuilder.com/sv/](https://recombuilder.com/sv/) · [Markdown](https://recombuilder.com/sv/index.md) · [Integritet](https://recombuilder.com/sv/privacy.md) · [Villkor](https://recombuilder.com/sv/terms.md) · [Tillgänglighet](https://recombuilder.com/sv/accessibility.md)
- Română (Romanian, `ro`): [https://recombuilder.com/ro/](https://recombuilder.com/ro/) · [Markdown](https://recombuilder.com/ro/index.md) · [Confidențialitate](https://recombuilder.com/ro/privacy.md) · [Termeni](https://recombuilder.com/ro/terms.md) · [Accesibilitate](https://recombuilder.com/ro/accessibility.md)
- Ελληνικά (Greek, `el`): [https://recombuilder.com/el/](https://recombuilder.com/el/) · [Markdown](https://recombuilder.com/el/index.md) · [Απόρρητο](https://recombuilder.com/el/privacy.md) · [Όροι](https://recombuilder.com/el/terms.md) · [Προσβασιμότητα](https://recombuilder.com/el/accessibility.md)
- Dansk (Danish, `da`): [https://recombuilder.com/da/](https://recombuilder.com/da/) · [Markdown](https://recombuilder.com/da/index.md) · [Privatliv](https://recombuilder.com/da/privacy.md) · [Vilkår](https://recombuilder.com/da/terms.md) · [Tilgængelighed](https://recombuilder.com/da/accessibility.md)
- Suomi (Finnish, `fi`): [https://recombuilder.com/fi/](https://recombuilder.com/fi/) · [Markdown](https://recombuilder.com/fi/index.md) · [Tietosuoja](https://recombuilder.com/fi/privacy.md) · [Käyttöehdot](https://recombuilder.com/fi/terms.md) · [Saavutettavuus](https://recombuilder.com/fi/accessibility.md)

## Policies
- [Privacy policy](https://recombuilder.com/privacy.md): no database, what is sent where and for how long, analytics only with consent, GDPR, PIPEDA, and CCPA
- [Terms](https://recombuilder.com/terms.md): terms of use
- [Accessibility](https://recombuilder.com/accessibility.md): WCAG 2.2 AA conformance (meets ADA and AODA web standards) and how to get help

## About the makers
- [How RecomBuilder was built](https://recombuilder.com/index.md#faq-built): built with AI coding (vibe coding) on Replit
- [Hire a team to build with AI coding](https://recombuilder.com/index.md#faq-hire): professional vibe coding services through [AIDrivenSites.com](https://aidrivensites.com/)
- [About AIDrivenSites.com](https://recombuilder.com/index.md#faq-aidrivensites): websites built on Replit that owners change in plain language
- [About DigitVibe](https://recombuilder.com/index.md#faq-digitvibe): applied AI consulting, training, and development ([digitvibe.com](https://digitvibe.com/))
- [About Mohammad Keyhani](https://recombuilder.com/index.md#faq-keyhani): professor, applied AI speaker and advisor, and builder ([mohammadkeyhani.com](https://mohammadkeyhani.com/))

## Optional
- [More from the maker](https://mohammadkeyhani.com/building): other projects by [Mohammad Keyhani](https://mohammadkeyhani.com/)