A Bitcoin wallet you download once.

Bertha is one file. It runs on your machine, holds your own keys, and never talks to a server of ours — because there isn't one.

Download Bertha

sha256 · 3f9a2c7e41b8d05639af2c1e8b74d6a0c93f5e2178bd4a6c0e93f5e2178bd4a6c

How it works

Download itOne HTML file. Open it in any browser, on your computer or your phone.

Set it upBertha makes a key on your machine. You write it down, then type it back to prove you have it.

Use itAdd BSV, send BSV. A payment lands in about a second.

What it doesn't do

No account, no email, no sign-up. No server holding your money or your keys. Nothing reports back to us about what you send or who you send it to.

Every payment you receive uses a new address, so nobody can watch one address and see your whole balance. That's hygiene, not anonymity — Bitcoin transactions are public, and anyone who knows one of your addresses can follow it from there.

Read this before you put money in it

The key you write down is the only backup. It isn't stored anywhere else, and we can't see it, reset it, or recover it for you. Lose the paper and clear your browser, and the money is gone permanently.

Bertha is for small amounts you spend — a couple of dollars for a game, a tip, a download. Savings belong somewhere you can't lose with a browser setting.

Taking payments on your site

Bertha doesn't plug into your page. Your site watches its own address, and when the payment shows up, you act on it. No SDK to trust, no key exchange, nothing of ours running in your users' browsers.

watch(myAddress, 500, (txid) => {
  startGame();
});

That's a small script you host yourself. It talks to a public block explorer, not to us.

Checking what you downloaded

The hash under the download button is also published on chain, where it can't be edited after the fact. Run shasum -a 256 bertha.html on the file you got and compare. If the two don't match, you're not holding our file.