Non-custodial Litecoin <-> Bitcoin atomic swaps in the browser, on testnet (plus Monero into either), with a hub to learn the testnets

Litecoin has some atomic-swap history: the first on-chain LTC<->BTC atomic swap happened back in 2017. I wanted that as something you can just do from a browser tab any time, on testnet, so I built TestnetSwap: non-custodial cross-chain atomic swaps that run entirely client-side.

The Litecoin/Bitcoin side (tLTC <-> tBTC) is a straight HTLC swap: a hashlock plus timelocks, both chains secp256k1 P2WSH. You sign both legs yourself, so nobody ever takes custody, and if the other side stalls or vanishes, you reclaim what you locked once the timelock passes. It also swaps Monero (tXMR/sXMR) into tLTC or tBTC with a cross-curve adaptor-signature construction, but the LTC/BTC HTLC path is the one that's proven end to end on-chain; the Monero side is more experimental and its upstream crypto isn't formally audited.

It's a multi-maker network: anyone can run a maker, and which one fills your swap never affects your safety. Max amounts are kept small since the liquidity is self-funded from my testnet pool and faucet.

Alongside the swap I launched TestnetHub, a place to actually learn the Bitcoin, Litecoin, and Monero testnets: step-by-step guides (transactions, confirmations, fees, UTXOs, keys and seeds, running a node, swaps), per-chain pages, a glossary, a live status page, and a companion repo of short, runnable Python and JavaScript examples. The swap also runs inside TestnetWallet now, if you'd rather do it from a wallet.

Testnet only, so the coins are worthless by design, and it's all open source (AGPL). Grab test coins from the faucet; no token, no signup.

Swap: https://testnetswap.com

Learn the testnets: https://testnethub.com

Code examples: https://github.com/Tech1k/testnet-examples

Writeup: https://testnetswap.com/whitepaper

Wallet: https://testnetwallet.net

Source: https://github.com/Tech1k/testnetswap

Still in active development. Feedback and bug reports welcome.