QR Code API

Live instance: https://qr.lifestep.io — try /health, and see /openapi.json for the full spec. Free, no signup.

Self-host it: docker compose up -d (see below). MIT licensed.

A small, stateless FastAPI service that generates QR codes from text or URLs. It returns either PNG bytes or an SVG document and is suitable for placing behind an API gateway such as RapidAPI.

Run locally

Requires Python 3.12 or newer.

python3.12 -m venv .venv
.venv/bin/pip install -r requirements-dev.txt
PYTHONPATH=. .venv/bin/uvicorn app.main:app --host 127.0.0.1 --port 8085

Open http://127.0.0.1:8085/docs for interactive OpenAPI documentation.

API

Both QR endpoints accept these values:

Field	Required	Default	Rules
data	yes	—	1–2000 characters
format	no	png	png or svg
scale	no	6	integer from 1 to 20
border	no	4	integer from 0 to 16
dark	no	000000	six-character RGB hex, without #
light	no	ffffff	six-character RGB hex, without #

GET /qr

curl --get 'http://127.0.0.1:8085/qr' \
  --data-urlencode 'data=https://example.com' \
  --data 'format=png' \
  --data 'scale=6' \
  --output qr.png

SVG with custom colors:

curl --get 'http://127.0.0.1:8085/qr' \
  --data-urlencode 'data=Hello world' \
  --data 'format=svg' \
  --data 'dark=172554' \
  --data 'light=eff6ff' \
  --output qr.svg

POST /qr

curl 'http://127.0.0.1:8085/qr' \
  --header 'Content-Type: application/json' \
  --data '{"data":"https://example.com","format":"png","scale":8,"border":4}' \
  --output qr.png

Other endpoints

• GET /health returns service status and version.
• GET / returns a minimal usage page.
• GET /openapi.json returns the OpenAPI schema.

Docker

docker compose up --build

The Compose service is available at http://127.0.0.1:8085. Stop it with docker compose down.

Tests

python3.12 -m venv .venv
.venv/bin/pip install -r requirements-dev.txt
PYTHONPATH=. .venv/bin/pytest -q

Honest limits

• The API holds generated images in memory and is intended for small, individual requests.
• The 2000-character input limit is an API ceiling, not a guarantee that every value can fit in a QR symbol. Encodability also depends on character encoding; unencodable inputs return HTTP 422.
• There is no authentication, per-customer quota, rate limiting, billing, caching, persistence, or abuse protection in this service.
• Very low color contrast can produce a QR code that scanners cannot read. The API validates color syntax, not contrast or scan reliability.
• SVG output is generated from the submitted data and should be served with the declared image/svg+xml content type.

RapidAPI-ready note

The stateless HTTP interface, CORS support, stable query/body schema, health endpoint, and OpenAPI document make the service straightforward to put behind RapidAPI or another gateway. Before publishing, configure gateway authentication, quotas, rate limits, request-size and timeout limits, monitoring, HTTPS, and commercial terms. None of those gateway controls are simulated by this repository.

Related free tools

• CLAUDE.md Auditor - paste your rules file and see which rules an agent cannot reliably follow
• XLSX Inspector — check workbooks for macros, external links and hidden sheets
• DNS and SPF Check — records, SPF, DMARC and TLS expiry
• Email Validator — syntax, MX, disposable and role addresses
• QR Code Generator — free PNG and SVG API, no signup
• agent-watch
• ai-code-review-prompts
• claude-md-patterns
• claude-code-orchestration-ko
• xlsx-inspector-api
• domain-info-api
• email-validator-api
• Agent Ops for VS Code - review prompts and agent rules in the Command Palette (VSIX install)
• Go Exec Format Doctor Action - CI gate for binary architecture mismatches

The paid guide collection is available at lifestep1.gumroad.com.