Payment solution
Breez SDK: crypto payment solution
The verdict
Breez SDK is a developer toolkit for building self-custodial Lightning into your own app. A typical merchant cannot use it as-is; it is for the developer who would build a merchant product on top of it.
- Who holds the funds
- Merchant-controlled
- Who holds the keys
- Merchant
- Self-hosting
- Not required (hosted)
- Lightning
- Yes
- Fiat settlement
- No
- Bank settlement
- No
Best for: Product teams and developers building a custom self-custodial Lightning app or wallet.
Poor fit: Any merchant who wants to accept crypto without commissioning custom software.
Biggest tradeoff: Breez SDK is genuinely strong developer infrastructure: self-custodial, open-source, multi-language, with good Lightning support. But it is a building block, not a product. The entire merchant experience, POS, refunds, reporting, must be built, which is why it is not merchant-ready.
What it is
Breez SDK is a developer toolkit for embedding self-custodial Lightning payments into an app. It comes in flavors (the maintained Nodeless/Liquid and the current flagship Spark, a Bitcoin L2 with stablecoin support; the older Greenlight is deprecated), with multi-language bindings and a reference wallet app.
What it is not
It is not a merchant product. It is not a POS, a checkout, a wallet a merchant just installs, or a gateway. There is no merchant surface at all: no refunds, reporting, or accounting until a developer builds them. A merchant cannot use it without commissioning custom software.
How the payment flow works
A developer integrates the SDK into an application, which then holds a self-custodial wallet for its user. Payments settle in Bitcoin or Liquid (and stablecoins on Spark) to that wallet. Everything a merchant would see, the register, the receipt, the report, is something the developer must build.
Custody, keys, and settlement
The most important thing about any crypto payment solution is who controls the money and what happens if the provider goes away. Here is the structured answer, from primary sources.
- Custody
- Merchant-controlled
- Key control
- Merchant
- Fiat settlement
- No
- Bank settlement
- No
- Settlement timing
- Instant
- Settles in
- Cryptocurrency
- Backup and recovery
- Merchant
Conversion: Breez SDK is self-custodial: keys are held by the end user of the built app. There is no fiat conversion or bank settlement; the Spark flavor adds stablecoin support on a Bitcoin L2.
Getting your money: Funds live in the wallet of the app a developer builds, controlled by that app's user via a seed. Recovery is restore-from-seed; whether balances remain spendable if Breez swap/API infrastructure is down is not fully documented.
If the provider or hosted service becomes unavailable
Payments stop, but existing funds remain merchant-controlled.
Funds are self-custodial in the app built on the SDK, recoverable from the user's seed, so they remain merchant-controlled. However, some flows depend on Breez swap and node infrastructure, and whether balances stay fully spendable if that infrastructure is unavailable is not completely documented.
What you have to operate
As a merchant, nothing, because you cannot use it directly. As the developer who adopts it, you own and operate the entire application built on the SDK, including its infrastructure and updates.
Ongoing maintenance: Full software ownership: the built app, its updates, and its infrastructure.
Support: Developer documentation and community; not a merchant support channel.
Who this is right for
A product team or developer building a custom self-custodial Lightning app or wallet, who wants a well-supported, open-source foundation to build on.
Who should skip it
Any typical merchant. If you do not employ developers to build a payment app, this is not something you can use; you want a finished product instead.
Our evaluation
Pricing
- Setup
- $0 (SDK) (the SDK is free; building the app is the real cost)
- Transaction fee
- Depends on flavor (Liquid/Lightning/swap fees; Spark end-user fees not published)
The SDK is free and open-source. The real cost is commissioning and maintaining the app built on it. Spark end-user fees are deferred to an external page that was not retrieved; treat them as unconfirmed. Last verified 2026-07-11.
Limitations
- It is an SDK, not a merchant product: a developer must build the entire experience.
- No POS, checkout, refunds, reporting, or accounting out of the box.
- No fiat conversion or bank settlement.
- Spark end-user fees are not published (deferred to an external page).
- Whether funds stay spendable during Breez infrastructure outages is not fully documented.
CryptoLic Lab
CryptoLic does not stop at reading documentation. We independently validate what vendors claim by setting things up and running them ourselves, then we publish what we actually observed. For this solution, that hands-on validation is not scheduled. Nothing below is marked verified until we have tested it, so you can trust a "verified" label when you eventually see one.
| What we will verify | Status |
|---|---|
| Confirm it is a developer SDK, not a merchant product | Pending verification |
| Spark fee schedule | Pending verification |
| Provider-outage spendability | Pending verification |
If you control the keys, you own the security. The The Merchant Security Playbook covers backups, recovery, and keeping funds safe.
Whichever solution you choose, the crypto has to reconcile against your books. The The Merchant Accounting & Bookkeeping Toolkit gives you a routine and a clean year-end package for your CPA.
Sources and verification
Last content review 2026-07-11 Documentation verified
- Custody
- 2026-07-11
- Settlement
- 2026-07-11
- Pricing
- 2026-07-11
- Availability
- 2026-07-11
- Kyc
- 2026-07-11
- Supported assets
- 2026-07-11
- Integrations
- 2026-07-11
- Refunds
- 2026-07-11
- Open source
- 2026-07-11
- Content reviewed
- 2026-07-11
- Editorial update
- 2026-07-11
- Breez Supports: Breez SDK is developer infrastructure for embedding Lightning
- Breez SDK docs Supports: SDK for developers; self-custodial; no merchant surface
- Breez SDK - Spark Supports: Spark is the current flagship flavor; stablecoin support; Greenlight deprecated
- breez GitHub org Supports: Active multi-language SDK
- breez-sdk-liquid LICENSE Supports: MIT license
- misty-breez Supports: Reference wallet app (Misty Breez)
Change log
- 2026-07-11 Initial publication as the reference not-merchant-ready case. Documentation review complete; Greenlight noted as deprecated, Spark as the current flavor.
Spotted something out of date? Send a correction. We verify every submission against primary sources; vendor contact never changes a rating.
Questions
Can my business use Breez SDK to accept crypto?
Not directly. Breez SDK is a developer toolkit, not a finished product. A merchant cannot use it without a developer building an application on top of it. If you do not have engineers, you want a ready-made solution instead, which is exactly why we mark this not merchant-ready.
Is Breez SDK self-custodial?
Yes. Keys are held only by the end user of the app built with the SDK. That is a genuine strength, but it is a property of the toolkit, not a merchant experience you can buy.
Why does CryptoLic cover an SDK a merchant cannot use?
To be useful precisely by saying so. Vendors and AI summaries sometimes present SDKs as if they were products. We include Breez SDK to draw the line clearly: this is for your developer, not for you, and no amount of capability changes that.
How this compares
Every solution we cover is evaluated the same way. Here is where the others land.
| Solution | Category | Readiness | The short version |
|---|---|---|---|
| IBEX | Infrastructure or developer platform | R1 Not merchant-ready | IBEX is Lightning and settlement infrastructure delivered through a single API for banks, fintechs, and platforms. A typical merchant cannot use it directly; a developer must build on it. |
| BTCPay Server | Self-hosted acceptance platform | R3 Workable with effort | BTCPay Server is the reference self-custody answer: free, open-source software that takes Bitcoin and Lightning straight to your own wallet, in exchange for running and maintaining a server. |
Compare it against the others in the Payment Solutions Decision Center, or start from what you actually need.
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