PaperLens

The AI document explainer for the rest of the world. Snap a photo of any official document — lease, contract, insurance policy, medical bill, tax letter — and get a plain-language summary in your language, with the risky clauses flagged and the right questions to ask.

Live: https://printer-olive.vercel.app Plan: plan.md · Setup: SETUP.md · Deploy: DEPLOYMENT.md

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Why this exists

Most people sign documents they don't fully read. The ones who do read them often don't understand the language — literally (non-native English speakers in a US lease) or technically (anyone reading their own insurance policy). PaperLens fixes both: vision + LLM + 20+ locales on a single screen, with privacy by default (uploads auto-purge).

This repository is public for transparency. Code is licensed under MIT — fork and build on it freely.

Stack

• Next.js 14 (App Router) + Tailwind, hosted on Vercel
• Supabase Postgres + Auth + Storage (free tier)
• Google Gemini 2.5 Flash for analysis (free tier; Hugging Face fallback)
• Polar.sh for payments (Merchant of Record; auto-collects VAT in 80+ countries; accepts Saudi sellers; ~4% + $0.40 per transaction)
• GitHub Actions for all crons + CI/CD (unlimited free minutes on public repos)
• Edge TTS, Pexels, Cloudflare Turnstile, Upstash Redis, Resend, Sentry, Vercel Analytics — all free tiers

Designed to run on $0/month until paid users justify upgrading individual pieces.

Quick start (local dev)

nvm use            # Node 22 from .nvmrc
npm install
cp .env.local.example .env.local   # then fill in keys (see SETUP.md)
npm run dev        # http://localhost:3000

npm run ci         # mirrors GitHub Actions: typecheck + lint + test + build

You don't need most keys to develop locally — the public landing page and waitlist form work with just NEXT_PUBLIC_SUPABASE_URL + NEXT_PUBLIC_SUPABASE_ANON_KEY. To test /api/analyze you need GEMINI_API_KEY and SUPABASE_SERVICE_ROLE_KEY.

Architecture in one diagram

                  ┌─────────────────────────────────────────┐
                  │   GitHub Actions (free, unlimited)     │
                  │   ┌────────┐ ┌──────┐ ┌────────────┐  │
                  │   │  CI    │ │ E2E  │ │ crons:     │  │
                  │   │  lint  │ │      │ │ cost-cap   │  │
                  │   │  test  │ │      │ │ short-form │  │
                  │   │  build │ │      │ │ pseo-pages │  │
                  │   └────────┘ └──────┘ └────────────┘  │
                  └────────────┬───────────────────────────┘
                               │ deploy / call /api/cron/*
                               ▼
              ┌──────────────────────────────────────────┐
              │   Vercel — Next.js 14 (App Router)      │
              │                                          │
   user ─────►│   /          /[locale]    /upload        │
              │   /pricing   /dashboard   /api/*         │
              │                                          │
              │   /api/analyze  ◄── the only paid call   │
              │     │   gates: Turnstile · rate-limit ·  │
              │     │          quota · file-size · auth  │
              │     ▼                                    │
              │   lib/ai/router  ──►  Gemini  ──►  HF    │
              │   ProviderError → fallback chain         │
              └────────────┬───────────────────────────┘
                           │
                           ▼
        ┌──────────────────────────────────────────────┐
        │   Supabase                                   │
        │   tables: profiles, documents, analyses,     │
        │           subscriptions, app_config,         │
        │           analyze_calls, waitlist            │
        │   storage: documents (private bucket)        │
        │   RPC: try_consume_free_quota,               │
        │        get_user_tier, get_today_spend_usd    │
        └──────────────────────────────────────────────┘

Spend safety (the "never lose money" layer)

Every cost surface has a hard ceiling and a soft circuit-breaker:

Layer	Cap
Google Cloud Billing budget	Hard cap (e.g. $30/mo) — Gemini stops
Vercel Spend Mgmt	Project pauses at threshold
Supabase	No card on file → can't be billed past free tier
/api/cron/cost-cap	Hourly: flips analyze_paused if today's spend > prorated daily allowance
Per-user free quota	3 docs/mo, atomic decrement in Postgres
IP rate limit	5 analyze req/IP/hour via Upstash Redis
Cloudflare Turnstile	Bot floods blocked at the edge
File size + page count	Server rejects > 20 MB / > 50 pages on free tier

If every cron and every gate above fails, the Google Cloud budget is the floor. You will never be billed more than that.

Plan & North Star

• Month 6: $5K MRR · Month 12: $20K MRR · Year 3: $1M ARR
• See plan.md for the full roadmap, kill criteria, and the four-tier B2C → small-team → API → embed-partners ladder that takes us to $1M.

Built by

Mara — a tiny solo team. If PaperLens helps you, the maintainers keep the lights on with coffee:

• ☕ Team: https://buymeacoffee.com/iammara
• ☕ Developer: https://buymeacoffee.com/justabdulaziz10

Documentation

• plan.md — Full $1M-ARR plan, marketing playbook, kill criteria
• SETUP.md — Every manual step the founder needs to do
• DEPLOYMENT.md — Vercel + Polar + Supabase deploy notes
• CONTRIBUTING.md — How to file issues / send PRs
• SECURITY.md — Responsible disclosure
• CODE_OF_CONDUCT.md — How we treat each other
• marketing/ — Lifecycle emails, SEO, short-form scripts
• LICENSE — MIT

Status

The waitlist landing page + the /api/analyze pipeline (Gemini + HF fallback, with all gates) are live. The signed-in upload UI, pricing page, and Polar.sh checkout ship in the next sprint. See plan.md "12-week build" for the schedule.

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PaperLens is not legal, medical, tax, or financial advice. It explains what your documents say, in plain language. For decisions that matter, talk to a qualified professional.