Black Koi
Wallet
Learn Bitcoin by doing it.
Coming Soon on Google Play
Free forever — no sign-up required
Learn Bitcoin by doing it.
Every transaction you make happens on Signet — a test network that works identically to Bitcoin. Coins have no monetary value. Mistakes have no consequences. The experience is completely real.
The built-in faucet sends practice sats to your wallet during the tutorial. No forms, no captcha, no waiting — just tap, receive, and keep learning.
From wallet creation to seed phrases, change addresses to mempool fees — each tutorial is a live exercise, not a lecture. Touch every concept before you trust real money to it.
Every Bitcoin term is explained three ways — simple, analogy, and technical. Tap any highlighted word, anywhere in the app, to read it at the level that makes sense to you right now.
Progress through four tiers — Young Koi, Swift Current, Upstream Journey, Dragon Gate. Complete all tutorials, pass the competency quiz, and unlock real Bitcoin mainnet access within the same app.
When you're ready, return your practice sats to the faucet so the next student can use them — then switch to mainnet. Same app. Same wallet. Real Bitcoin, earned through readiness.
Most Bitcoin education is passive — videos, articles, podcasts. Black Koi Wallet is the only app that combines a complete structured curriculum with a live functional wallet on a real test network. You don't simulate learning. You learn.
Black Koi is free forever — no premium tier, no ads, no accounts. The source code is open. The mission is simple: anyone who wants to understand Bitcoin self-custody should be able to practice it safely before they risk a single satoshi.