Pegcheck

I built a stablecoin API with no coding background — now it's powered by Chainlink and logs depeg events on the blockchain

Six weeks ago I couldn't write a line of code.

Today I have a live authenticated B2B SaaS API, Stripe payments, auto key generation, a customer dashboard, Chainlink price feeds, Proof of Reserve data, and a smart contract logging depeg events permanently on the Ethereum blockchain.

Here's the honest story of how it happened.

Where it started

I'd been doing resale — buying box pallets, selling on Facebook Marketplace. Decent side income but not a future.

I kept thinking about building something. Not because I had a technical background — I didn't. But because I couldn't hold down a job. Every workplace, every manager, every "how do you think you've done?" I knew I was better than the situation I was in.

So I started building PegCheck.

What PegCheck is

A stablecoin depeg monitoring tool. It tracks USDT, USDC, USDS, PYUSD, FDUSD, RLUSD, TUSD and Ethena in real time — and alerts you the moment any of them loses its $1 peg.

The core insight was simple: most stablecoin price feeds rely on a single source. One source can be wrong, manipulated, or just slow.

So I built a median across 6 independent sources — CoinGecko, Coinbase, Binance, Kraken, DefiLlama, and Chainlink. That's 1,500+ data points distilled into one reliable number.

No other stablecoin monitoring tool does this specifically.

The pivot to B2B

After a few months I had a decent consumer app. Real users, real data, working email alerts.

Then I realised — the real value wasn't the app. It was the data underneath it.

So I built a REST API on top. Five endpoints, Bearer token auth, Stripe checkout, auto key generation, customer dashboard, full docs. Three pricing tiers — Starter £99/month, Pro £249/month, Enterprise £499+.

Built it in a weekend with Claude Code.

The Chainlink integration

Adding Chainlink as a data source was the obvious next move. But I went further.

I deployed a smart contract on Sepolia testnet — PegCheckDepegLogger. Every time PegCheck detects a real depeg event, it writes it permanently to the Ethereum blockchain.

Immutable. Public. Verifiable by anyone.

You can see the contract and the live event log at pegcheck.uk/onchain.

I also integrated Chainlink Proof of Reserve — pulling verified on-chain reserve data for supported stablecoins directly from Chainlink's oracle network.

Where I'm at

Live product. Real data. Chainlink verified. On-chain depeg logging.

Zero paying customers. That's the next problem.

The product is ready. Now I need to find the developers building wallets, exchanges, and DeFi apps who need exactly this.

If that's you — 30 day free trial at pegcheck.uk/developers. No card needed.

And if you've been through the "zero to first customer" stage — I'd genuinely love to hear what worked for you.