28 Technology Stack

This page lists the technologies HealthBook AI (internal code name: BabyCare) actually uses, layer by layer. Every version is quoted from a file in the repository, and the source file is named in each table. requirements.txt holds the allowed ranges; requirements.lock (generated with uv pip compile requirements.txt --universal) holds the exact versions installed in CI and in the Docker image. Where a file gives no version, the table says so.

Responsibilities

• Keep the runtime small enough for free hosting tiers (one container, no build step for the web app).
• Prefer libraries that run locally (OCR, PDF, image analysis) over remote services.
• Pin everything that reaches production through the lockfile.

Runtime and platform

Component	Version	Source	Use
Python	3.12 (python:3.12-slim image)	Dockerfile, ci.yml (python-version: '3.12')	API, worker, scripts
Tesseract OCR engine	apt package tesseract-ocr, no version pinned	Dockerfile, ci.yml	Local OCR for scanned pages and photos
PostgreSQL	postgres:17 image	ci.yml, docker-compose.postgres.yml	CI staging suite, self-hosted database
Node.js	20	ci.yml (node-version: '20')	JS syntax checks, Playwright, Expo tooling
Java	Temurin 17	ci.yml (actions/setup-java@v5)	Android Gradle build
GitHub Actions	checkout@v4, setup-python@v5, setup-node@v4, setup-java@v5, upload-artifact@v4	ci.yml	CI
EAS CLI	>= 16.0.0	mobile/eas.json	Optional Expo build profiles

Backend (Python)

Library	Range (requirements.txt)	Locked (requirements.lock)	Use in the code
FastAPI	>=0.115,<1	0.142.2	HTTP API, routers, dependencies (api/main.py)
Starlette	(via FastAPI)	1.7.0	Static files, middleware, threadpool
Uvicorn ([standard])	>=0.34,<1	0.54.0	ASGI server (Dockerfile command)
Pydantic	>=2.9,<3	2.13.5	Request validation models
python-multipart	>=0.0.20,<1	0.0.32	Document and photo uploads
SQLAlchemy	>=2.0,<3	2.1.3	ORM, EncryptedText type decorator (api/crypto.py)
Alembic	>=1.16,<2	1.20.0	Schema migrations run on startup (api/migrate.py)
psycopg ([binary])	>=3.2,<4	3.3.6 (+ psycopg-binary 3.3.6)	PostgreSQL driver, postgresql+psycopg:// URLs
cryptography	>=50,<51	50.0.2	Fernet encryption of files and clinical text; EC P-256 keys for VAPID
PyMuPDF	>=1.24,<2	1.28.2	PDF validation, text layer, page rendering, PDF appendix (api/extract.py, api/export_pdf.py)
pytesseract	>=0.3.13,<1	0.3.13	Python binding to Tesseract
Pillow	>=11,<13	12.3.0	Image validation, thumbnails, stool-photo colour analysis
pillow-heif	>=1,<2	1.8.0	Optional HEIC decoding
ReportLab	>=4.2,<5	4.5.1	PDF export body and vector charts
httpx	>=0.27,<1	0.28.1	Supabase Storage REST calls, Expo push, vision provider, test client
pywebpush	>=2,<3	2.5.0 (+ py-vapid 1.9.4, http-ece 1.2.1)	Web Push delivery (api/push_web.py)
python-dateutil	>=2.9,<3	2.9.0.post0	Age arithmetic for the vaccination reference chart
python-dotenv	>=1.1,<2	1.2.4	Loads .env (api/config.py)
tzdata	>=2025.2	2026.5	IANA zones for per-profile timezones (zoneinfo)
filelock	>=3.18,<5	4.0.9	Migration lock, single reminder-worker lock
pytest	>=8,<10	9.1.1	Backend test suite

The email sender (api/mailer.py) uses the standard library (urllib.request, smtplib), not an SDK. The camera worker can read real streams with opencv-python-headless, which is not in requirements.txt; without it the worker raises an explicit error or runs in simulation mode.

Web frontend

Component	Version	Source	Notes
Application code	none (no framework, no bundler)	web/*.js, web/index.html	Plain script files loaded with defer; node --check in CI
Service worker	cache name babycare-shell-v16	web/sw.js	Shell cache only; /api/ never cached; Web Push display
Web app manifest	n/a	web/manifest.webmanifest	Installable app
Charts	in-house	web/charts.js, web/analytics.js	No charting library
@playwright/test	^1.63.0	package.json (devDependency)	Browser specs in tests/browser/

Android app (mobile/package.json)

Package	Version
expo	~54.0.0
react	19.1.0
react-native	0.81.5
typescript (dev)	~5.9.2
@types/react (dev)	~19.1.10
expo-secure-store	~15.0.7
expo-notifications	~0.32.12
expo-document-picker	~14.0.8
expo-image-picker	~17.0.8
expo-image-manipulator	~14.0.8
expo-file-system	~19.0.24
expo-sharing	~14.0.8
expo-clipboard	~8.0.8
expo-constants	~18.0.14
expo-build-properties	~1.0.10
expo-dev-client	~6.0.21
react-native-safe-area-context	~5.6.0
react-native-svg	15.12.1

overrides pin postcss to ^8.5.28 and uuid to ^11.1.1. The app identifier and version (1.1.0, versionCode 2) come from mobile/app.config.js.

Hosted services

Service	Plan stated in code	Used for	Configured in
Render	free web service, Docker runtime	FastAPI API	render.yaml
Firebase Hosting	Spark	Static web app and doctor.html	firebase.json, .firebaserc
Supabase PostgreSQL	free, session pooler	Database	DATABASE_URL
Supabase Storage	free, private bucket	Encrypted originals and photos	api/storage.py, deploy/supabase/setup.sql
Supabase pg_cron + pg_net	free extensions	Scheduler wake-up	deploy/supabase/setup.sql
Brevo or Resend	HTTPS email APIs	Password-reset email	api/mailer.py
Expo push service	exp.host push API	Android reminders	api/worker.py
Browser push services	RFC 8030 + VAPID	Web reminders	api/push_web.py
OpenAI-compatible vision endpoint	optional, off by default	Consented transcription	api/providers.py

Bundled assets

DejaVu Sans and DejaVu Serif TrueType fonts in api/assets/fonts/ are embedded in PDF exports so output does not depend on system fonts.

Implementation

requirements.txt, requirements.lock, package.json, mobile/package.json, mobile/eas.json, Dockerfile, .github/workflows/ci.yml, docker-compose.postgres.yml.

Related pages

System Architecture · Backend Architecture · Web Application Architecture · Android Application Architecture · Deployment and CI/CD · Design Decisions