Cashu Pay Server

Accept Bitcoin without the complexity

Payment gateways want your ID. BTCPay Server needs a VPS and Docker expertise. CashuPayServer is the middle ground: a BTCPay-compatible gateway that runs on the PHP hosting you already have.

Public Key

npub18scydh6yusrkhe67f8uz9mnxxt5znae59ctvhxxpzefkf7xwnx4q0nalja

NIP-05 Address

cashupayserver@cashupayserver.org

Profile Code

nprofile1qqsrcvzxmazwgpmtua0yn7pzaenr96pf7u6zu9ktnrq3v5mylr8fn2spr3mhxue69uhkummnw3ezucmewp5x2unsw4hxktn5dajxz7gpzemhxue69uhhyetvv9ujuurjd9kkzmpwdejhgnskyy7

Publishing to

nostr.cypherpunk.today

relay.primal.net

offchain.pub

relay.damus.io

Author Public Key

npub18scydh6yusrkhe67f8uz9mnxxt5znae59ctvhxxpzefkf7xwnx4q0nalja

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Last Notes

2026-10-31 15:17:00 UTC

CashuPayServer v0.5.9-alpha is out — together with yesterday's v0.5.8, the result of a fourth audit that asked one question: can anyone lose money?
The most serious security one: if the same Cashu token was sent to two payment requests at the same moment, both turned "Paid ✓" while the shop received the money once. Now each shop receives one payment at a time.
The rest of the security and payment fixes:
- Late payments are collected again on busy shops. If the mint or your server was down for more than three days, a customer's payment could stay uncredited as long as new checkouts kept coming in.
- One price source can no longer move fiat prices. With the other providers down, a single bad answer could shift EUR, GBP or CAD prices by up to 25 %, and the wrong rate stuck.
- Backup mints are protected and looked after: removing one with open orders could hide a later payment, and money held there was never moved off retiring keysets.
- A store left behind by whoever claimed setup first (with their mint and their seed) could survive a recovery-code takeover. It is now removed.
But the interesting result: the worst risks to a shop's money were not attackers. They were things that quietly stop working. So 0.5.9 fixes those:
- Automatic withdrawals work above 10,000 sats. On a mint that reserves 1–2 % for Lightning fees, every automatic payout above roughly 10k sats failed, run after run, while the money piled up at the mint.
- Setup now asks where your money should go: paste your Lightning address, it is checked, and payouts happen by themselves. Or choose "Not now" and try it first.
- Customers are never told to pay twice. Paying at the last second used to show "Invoice expired, request a new one". Now the page says not to pay again, keeps checking, and turns to "Payment Complete" when the money arrives.
- Your shop hears about a payment at once, not on the next visitor.
- Alerts by email or a private Nostr DM (NIP-17) when customers can't pay, withdrawals keep failing, or a security update is out.
- A printable recovery sheet: your seed words plus every mint your store has used. The seed alone doesn't tell you which mints to restore from.
- No more white screens at install. Hosting problems now show a plain page with a message to send to your host.
One change in how you upgrade: the zip no longer has a folder of its own. Unpack it straight into your existing installation folder, keeping your data folder. If you unpack it into a new subfolder by mistake, setup notices and tells you which folder to delete.
- Standalone: unpack the new zip into your installation folder, replacing the old files, keeping your data folder.
- WordPress: upload the plugin and choose "Replace current with uploaded".
The database updates itself on your first visit.
About the audit: Opus 5.5 with the Cloudflare security-audit skill (https://github.com/cloudflare/security-audit-skill), plus separate passes for reliability, the customer at checkout, and a shop owner who has never used SSH. Every finding was reproduced in a sandbox and checked by independent verifiers before it counted.
👉 Download: https://github.com/jooray/cashupayserver/releases/tag/v0.5.9-alpha

2026-10-22 10:25:01 UTC

- reply

at the end of cashupayserver.org there's a donation widget, that checkout goes thorough the cashupayserver checkout.

2026-10-21 18:30:00 UTC

CashuPayServer v0.5.7-alpha is out — the second release from this October's three independent security audits, and it closes every code-side finding they left open.
If you've patched your PHP already, you can also upgrade CashuPayServer. If not, patching PHP is more important, go do that.
The most serious one was in the WordPress plugin: showing the seed phrase or downloading the database accepted any password, because the already-open admin session was the only check (but you still needed to be logged in as admin into WordPress). It now asks for your real WordPress password. MiniMax M3.1 found that one, and it is again the model that caught something the earlier scans missed.
The rest of the important fixes:
- Stranded-funds exports now reserve the money, so the same ecash cannot be handed out twice or spent while the token circulates.
- The setup wizard can no longer be re-entered to reset the admin password or keep a previous claimant's server address.
- Fiat pricing needs two independent sources to agree, so one bad provider cannot underprice invoices.
- An interrupted wallet backup no longer leaves a full copy of the database behind.
- Public token submissions are bounded, closing a request that could burn minutes of CPU.
- Trusted-proxy settings can no longer name the whole internet.
Upgrading takes a couple of minutes and there is nothing to configure:
- Standalone: upload the new files over the old ones, keeping your data folder.
- WordPress: upload the plugin and choose "Replace current with uploaded".
The database updates itself on your first visit.
Three audits, three models: DeepSeek 4.1 Flash 1017, Opus 5.5 and MiniMax M3.1 (Space Bunny). They found real issues at every level, including the WordPress one above.
What changed? We used the same models for previous audits, but this time we used the cloudflare security audit skill: https://github.com/cloudflare/security-audit-skill Highly recommended, it's good.
👉 Download: https://github.com/jooray/cashupayserver/releases/tag/v0.5.7-alpha

2026-10-19 19:45:00 UTC

CashuPayServer v0.5.6-alpha is out, and it's the most thoroughly reviewed release yet.
Three independent security audits went through CashuPayServer and its Cashu wallet library line by line. This release fixes what they found. If you take bitcoin payments with CashuPayServer, please upgrade, although no bug was remotely exploitable or critical.
What's new:
- Payment requests work with any standard Cashu wallet. Show a QR code, the customer pays, and the page turns to "Paid ✓" the moment the money arrives. Newer wallets also get the compact creqB format, a smaller QR code that's easier to scan.
- Payments and withdrawals are much harder to break in extreme conditions.
- Safer data out of the box. If your wallet database could be downloaded from the web, the dashboard tells you, and a new install can move its data to a safe place with one click.
Upgrading takes a couple of minutes, and there's nothing to configure:
- Standalone: upload the new files over the old ones, keeping your data folder.
- WordPress: upload the plugin and choose "Replace current with uploaded".
The database updates itself on your first visit.
Cheap PHP hosting, no node to run, bitcoin payments in your shop.
About the audits: We have always run Ai audits with all the models available. This round brings DeepSeek 4.1 Flash 1017, Opus 5.5 and MiniMax M3.1 (also known as Space Bunny). All of them found real bugs previous audits/models did not find. And we have run the heavyweights on CashuPayServer before. MiniMax M3.1 was the only one that found a higher severity bug, which all previous scans missed. Since it is free on OpenCode for a few days, run your security-critical code through it.
👉 Download: https://github.com/jooray/cashupayserver/releases/tag/v0.5.6-alpha

2026-09-25 10:37:00 UTC

CashuPayServer v0.5.5-alpha is out.
If you switched your store to a different mint on 0.5.4, payments could get stuck in "Processing". This release fixes it, and those payments are credited once you upgrade. It also runs on PHP 8.1 and 8.2 now, and a standalone install sitting inside a WordPress site's folder no longer answers 403.
WooCommerce shops can save the BTCPay plugin settings without the key being rejected, and a customer who retries paying an order gets the payment page instead of a 404.
The QR libraries used to load from CDNs, including on the admin page that can show your seed phrase. They ship with the app now.
There's also a signed emergency shutdown. If we ever find a hole that lets strangers take your money, we can publish a notice signed with a Nostr key, and installs on the affected versions stop until they're upgraded. Nothing moves your funds. If you'd rather not have it, turning off the update check in Settings turns it off too.
Reasoning for doing this in this blog: https://juraj.bednar.io/en/blog-en/2026/09/18/ten-ai-models-vs-embargoed-core-lightning-a-case-study-of-ai-for-auditing/ (Section "Signed kill switch"). I wish other Bitcoin projects included something like this.
Upload it over your old install and keep the data folder.
https://github.com/jooray/cashupayserver/releases/tag/v0.5.5-alpha

2026-09-10 04:36:00 UTC

CashuPayServer v0.5.4-alpha is out — a security and reliability release.
CashuPayServer lets a small shop accept Lightning payments by speaking BTCPay Server's API, so e-commerce plugins built for BTCPay work with it by just changing one URL. No node or BTCPay instance; it runs on ordinary PHP shared hosting and settles through a Cashu mint.
Four AI audits went over the server and the wallet library, and this release fixes what they found: fee handling on withdrawals, a double-spend path in exports, an amount-check bug, and an invoice-status check that stopped working after the first try.
Still alpha. Keep balances small and withdraw often (or automatically).
https://github.com/jooray/cashupayserver/releases/tag/v0.5.4-alpha

2026-07-18 11:37:00 UTC

CashuPayServer v0.4.1-alpha ⚡
Accept Lightning on the PHP hosting you already have.
This release is about not losing track of a single sat:
Recover funds from a previous mint — if a mint change ever stranded a balance, scan and export it back as a claimable token
Changing a store's mint now warns and offers export instead of silently stranding funds
New "Recent Transfers" ledger on the dashboard: every Lightning withdrawal, auto-withdrawal, token export and donation, in one place
Upgrading never touches your ecash — the DB is separate and migrates itself. Still alpha; start small, keep your seed safe.
https://github.com/jooray/cashupayserver/releases/tag/v0.4.1-alpha

2026-07-17 18:00:00 UTC

cashu-wallet-php v0.1.0 — first tagged release 🥜
A single-file, zero-dependency PHP implementation of Cashu. Drop
CashuWallet.php into any PHP 8 project and go.
Covers NUT-00/01/02/03/04/05/07/08/09/12/13/19/20 — including keyset v2,
NUT-13 HMAC derivation, DLEQ verification, and NUT-20 BIP340 quote locking.
Crash-safe operation journal, so you don't lose coins mid-swap or mid-melt.
284 tests, validated against the official Cashu spec vectors.
Still very alpha, feedback appreciated.
https://github.com/jooray/cashu-wallet-php/releases/tag/v0.1.0

2026-07-17 11:01:00 UTC

CashuPayServer v0.4.0-alpha is out ⚡
Accept Lightning payments on the plain PHP hosting you already have. Your existing BTCPay / WooCommerce plugin just works.
· Keyset v2 + correct NUT-13 derivation — your seed stays a real backup
· NUT-20 quote locking (BIP340) — a leaked quote id can no longer mint your money
· DLEQ verification + automatic keyset rotation
· Lightning withdrawals that reconcile instead of getting stuck
Still alpha: start small, keep your seed safe.
https://github.com/jooray/cashupayserver/releases/tag/v0.4.0-alpha

2026-07-02 06:52:00 UTC

CashuPayServer v0.3-alpha has some security and reliability fixes. Give it a try and definitely upgrade if you are using the older version.

2026-05-30 12:02:33 UTC

- reply

Yes, you can cash out automatically to a lightning address (not on-chain currently, although as mints support on-chain, this will be possible too!).
If you have woocommerce store with a btcpayserver plug-in, it works out of the box, yes, precisely because it is compatible.
For this specific scenario there is also a WordPress plug-in that will setup cashupay and configure the btcpayserver plugin automatically, so you don't even have to upload anything manually, just install the plugin and your integration is autoconfigured.
For other services you use the btcpay plugin compatibility exactly as you described.

2026-05-27 16:48:00 UTC

The biggest threat to the circular economy isn't regulation, but laziness. We outsource our payments to "convenient" gateways because we're afraid of the tech stack.
CashuPayServer was built to kill that fear. It’s a lightweight, PHP-based Lightning gateway that settles via Cashu. It’s as easy to install as a contact form and as private as a cash transaction.
Don't wait for the "official" circular economy. Build it on your own server today.

2026-05-15 10:37:00 UTC

If you need a KYC'd third-party gateway to accept Bitcoin, you aren't using Bitcoin. You're just using a slower, more expensive version of Stripe. Good for adoption for clients, but if you are a merchant, you're missing out.
True sovereignty means owning the checkout. CashuPayServer lets you accept Lightning payments directly on your own WordPress site (or anywhere where BTCPay is supported - prestashop, ...) without asking a corporate middleman for permission.
Yes, it runs on your $5/month hosting that you already have. No node/VPS/docker required. Just install as wordpress plugin or unzip (in case of non-wordpress install), configure and you are good to go.
https://cashupayserver.org/

2026-05-11 11:36:00 UTC

Why is it so hard to sell a digital PDF for Bitcoin without using a centralized platform that takes a 10% cut?
CashuPayServer is the missing link for the independent creator. It’s a one-click WordPress/WooCommerce plugin that turns any basic website into a professional Lightning storefront. Keep 100% of your sats. Own 100% of your data. Free and Open Source.
Your shop, your rules.

2026-05-04 15:59:00 UTC

Privacy isn't just for customers; it's for merchants too. Why should your payment processor know your turnover, your products, or your customer's identity?
CashuPayServer uses Cashu mints for settlement of Lightning payments. This creates a "privacy buffer" between your shop and the network. The mint sees the Lightning payment; you see the credit. Nobody sees the link between the two except you.
Why Cashu mint? The easiest way to accept Lightning and not run a Lightning node. And yes, it can immediately withdraw to a real non-custodial Lightning wallet.
Accept Lightning with "Stealth Mode" enabled.

2026-05-02 19:36:37 UTC

- reply

Can most shared hostings run C# code?
And which remote ln node? Blink?

2026-05-02 08:23:42 UTC

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Agreed that it is possible, but it's not only install. You need to maintain it.
Their page mentions only VPS for $10+, do you have tips for $2-$5 VPS? Might be useful for other projects. What Lightning node do you use in this low-cost setup?
Anyway - the point of CashuPay is that it can run on what you already have (PHP hosting for your e-shop). You don't need anything extra, not even $2 VPS. Just unzip and go.
P.S.: I am fan of BTCPay, if it's not a problem for you, run it, I also run one. This project is for people for whom the more complicated setup is a barrier to accepting Lightning.

2026-04-26 08:14:38 UTC

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I don't agree. It's still not running on the cheap PHP hosting. Yes, AI can deploy it, but you still need docker, or a way to run at least the main dot net daemon. Way different than unpacking a zip / installing a WordPress plug-in.
If anyone can run BtcPay, we're all for it and love the project. Cashupayserver is for those who can't do it for whatever reason.

2026-04-23 10:32:00 UTC

Most people think running a private Bitcoin payment server requires a $20/month VPS, Docker, and a sysadmin degree. It doesn't.
CashuPayServer is a Free and Open Source Lightning payment gateway that runs on standard, cheap PHP hosting. If you can host a WordPress site for $5/month, you can host your own Lightning payment gateway. Simple install. No terminal required. No complexity tax.
You can accept Lightning payments - clients don't need a Cashu wallet.
Stop overpaying for hosting you don't need. Use what you already have.
https://cashupayserver.org/

2026-04-06 09:20:28 UTC

Exactly!
Even your payment gateway has to be your...
#nevent1q…twd4

2026-02-12 13:20:00 UTC

2026 brought new rules in the EU. Lightning payments at shops now usually KYC you, because the shops use third parties.
Third-party gateways count as VASPs or CASPs or whatever buzzword they made up. It means they're licensed and forced to do it.
Customers hate the hassle and they won't pay with these gateways.
Run your own gateway. CashuPayServer on $3 shared hosting. No KYC, sign-ups, contracts.
It's still experimental though, test with small amounts. Your sats, your rules.

2026-02-10 16:11:39 UTC

Here's a video overview of what we are up to....
https://cashupayserver.org/cashupay-video.mp4

2026-02-10 16:09:53 UTC

Hello Nostr!
Have you tried CashuPayServer yet? We are a Cashu-based, but BTCPay API compatible payment gateway that runs on PHP hosting you already own.
You can accept Lightning payments in your store with very little friction. WooCommerce, PrestaShop or anything supported by BTCPayServer without the complexity. We even have a WooCommerce plug-in, so the install is really simple.
Give it a try!
https://cashupayserver.org/