PayPerFrame

Inspiration

Digital content pricing hasn’t evolved in 15 years. Users still face a simple but frustrating choice: Pay $4.99 upfront Or don’t buy at all What if you quit after 10 minutes? What if the course wasn’t what you expected? What if the audiobook narrator ruins the experience? That hesitation leads to zero revenue for platforms and lost value for users. We asked: What if pricing reflected actual engagement instead of blind commitment? PayPerFrame was born from that question.

What it does

PayPerFrame replaces flat pricing with real-time, engagement-based microtransactions. Users pay only for what they actually consume — down to the second. If they stop early, billing stops immediately. If they skip sections, those seconds aren’t charged. Instead of guessing value upfront, the system aligns pricing with real user behavior. It’s not a new streaming platform. It’s an infrastructure layer — like Stripe — for engagement-based payments.

How we built it

We built a full end-to-end system using: Solana Devnet for real on-chain transactions (test SOL) Session keys for silent micro-payments without wallet spam Off-chain batching (Redis + BullMQ) to reduce transaction load Helius webhooks for on-chain indexing Python pricing engine for dynamic engagement-based pricing Chrome Extension (Manifest V3) prototype integrated with YouTube Node.js + Fastify backend PostgreSQL + Redis Anchor smart contract on Solana Key Technical Innovation 1️⃣ Session Key Model User approves once with a spending cap. All microtransactions occur silently within that cap. No wallet popup spam. No per-second approvals.

2️⃣ Engagement-Based Oracle We record real on-chain payment sessions. Dynamic pricing adjusts using retention and skip behavior. High engagement → higher value High skip rate → lower price

3️⃣ Four-Layer Accidental Playback Protection Background tab detection “Still watching?” prompts Spending velocity alerts Spending caps enforced on-chain Trust is engineered, not assumed.

Technical Architecture

User → Extension → Backend → Solana Devnet → Helius → Pricing Engine → UI Transactions are real and visible on Solana Devnet Explorer. We use off-chain accumulation with periodic settlement to maintain scalability.

Challenges we ran into

🔐Wallet Custody & Signing Designing session keys that allow silent payments while preserving security was the biggest technical challenge. ⚖️ Engagement Detection “Actively consumed” required multi-signal gating: Tab visibility Playback progression Skip detection Inactivity protection

Accomplishments that we're proud of

🚀 Built real on-chain microtransactions on Solana Devnet — not a simulated demo. 🔐 Designed a session key system that enables per-second billing without wallet popup spam. ⚡ Implemented off-chain batching to reduce thousands of transactions into efficient settlements. 📊 Created a dynamic pricing engine based on real engagement data, not fixed assumptions. 🛡 Engineered multi-layer user protection (caps, inactivity detection, background tab pause). 🏗 Delivered a complete end-to-end infrastructure prototype within hackathon time.

What we learned

Blockchain isn’t the product — it’s the enforcement layer. Pricing models shape user psychology. Engagement is measurable, but never perfectly. Infrastructure ideas must balance economics, UX, and security. We didn’t just build a demo. We built a working economic system.

What's next for PayPerFrame

Today: Flat pricing forces commitment before experience. Tomorrow: Content unlocks progressively, priced by real engagement. PayPerFrame turns hesitation into revenue — without sacrificing fairness.

Built With

• bullmq
• crxjs
• css
• fastify
• pino
• postgresql
• react
• redis
• solana
• tailwind
• typescript
• vite
• zustand