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Crypto Payments & Payment Gateway Development

In short

A crypto payment system is the rails around the stablecoin: on/off-ramp, settlement, treasury, compliance, custody, and card spending. We build all of it in production, with real stablecoin-rails work behind us and a Wirex partnership for non-custodial card payments.

Luis Medeiros

Reviewed by Luis Medeiros, Field CTO at ProtofireLast reviewed: August 2026

$2B+
secured on Safe across 120+ EVM networks
60+
networks
250+
projects since 2016
1M+
developers (Solhint)
Trusted by teams building on-chain

Moving money on-chain looks simple until you build it. A real payment system has to bring users in from fiat, hold and settle value reliably, keep balances and books reconciled, stay compliant at every step, and let people actually spend what they hold. Stablecoins made the settlement layer fast and cheap, but the rails around them, on/off-ramp, treasury, compliance, custody, and card spending, are the parts that take real engineering to get right.

Protofire has shipped 250+ blockchain projects since 2016, and payment rails are a place we build in production, not in theory. We build cross-border stablecoin settlement into products through our stablecoin cross-border payments work: issuer and on/off-ramp orchestration, treasury and reconciliation, and Chainlink CCIP cross-chain settlement.

We built the DEX core and subgraph for Swarm, a BaFin-licensed DEX at launch where only KYC-verified wallets can trade. And we are partnering with Wirex to bring non-custodial card payments to blockchain projects, deploying Wirex's BaaS card infrastructure on-chain and integrating Wirex card payments into partner products.

We build the payment layer you need: stablecoin settlement rails, on/off-ramp orchestration, card spending, and the treasury, compliance, and custody around them, under your own brand. Take the full stack or the one rail you are missing. We maintain Solhint, the linter used by 1M+ developers, so the contracts moving your users' money hold to the standard we set for the ecosystem.

The crypto payment stack we build and operate

We build the rails on either side of the stablecoin transfer: on/off-ramp, settlement, treasury, compliance, custody, and cards.

01

On/off-ramp

Fiat-to-stablecoin entry and exit, integrating the ramp and PSP providers you choose, with KYC enforced at the edge.
02

Settlement rails

Stablecoin settlement on-chain: multi-issuer support (USDC, USDT), CCIP cross-chain settlement, and the accounting that keeps balances correct.
03

Cards & spending

Non-custodial card payment infrastructure through our Wirex partnership: the Wirex BaaS card stack on-chain and card integration into your product.
04

Treasury & reconciliation

Balance management, FX, and reconciliation between on-chain flows and your books, with reporting your finance team can use.
05

Compliance & custody

KYC, AML, and Travel Rule enforced at the rails, Safe or MPC custody, and Proof of Reserve where funds are held.
01

What we build: rails, gateway, and cards

Stablecoin payment rails

The settlement layer at the center of any crypto payment product. We build the flows that accept, hold, and settle value in stablecoins, with multi-issuer support (USDC, USDT), balance accounting that stays correct under load, and the oracle and price plumbing a payment system needs. This is delivered work: we build cross-border stablecoin settlement into products today.

On/off-ramp orchestration

The hardest part of a payment product is the fiat edge. We orchestrate on and off ramps between fiat and stablecoins, integrating the ramp and PSP providers you choose rather than locking you to one, with KYC enforced at the point of entry. We built the DEX core for Swarm Markets, a BaFin-licensed DEX at launch where only KYC-verified wallets can trade, so regulated venues are not new territory. Where customers keep euros in their own wallet, we build wallet-linked IBAN accounts, which mint an e-money token on each incoming SEPA payment.

Cards & non-custodial spending

Users want to spend what they hold. Through our partnership with Wirex, we bring non-custodial card payment infrastructure to blockchain projects: deploying the Wirex BaaS card stack on-chain for networks that need it, and integrating Wirex card payments into your product, so spending stays self-custodied rather than routed through a custodial middleman. Our crypto-backed cards blueprint documents how live card programs let customers spend on-chain balances while the program itself never takes custody, and the crypto acceptance blueprint covers the merchant side: stablecoins accepted at the till, merchants settled in euro on the terminals they already have.

Cross-border settlement

Stablecoin rails are at their strongest across borders. We build cross-border settlement into your product with CCIP cross-chain messaging, multi-issuer stablecoin support, and the treasury and reconciliation that keep a multi-currency, multi-chain flow correct, all under your own brand rather than a third party's.

Treasury, FX & reconciliation

A payment system is only as trustworthy as its books. We build the treasury layer: balance management across chains and issuers, FX handling, and reconciliation between on-chain flows and your accounting, with the reporting a finance and compliance team actually needs to sign off. A corporate treasury that pays suppliers in stablecoins from Kyriba, SAP or another TMS is covered on stablecoin payments from your treasury system.

Compliance, custody & reserves

Payments live under scrutiny. We wire KYC, AML, and Travel Rule checks into the rails and enforce them in code, integrate Safe multisig or an MPC custodian so funds are held to your risk model, and build Proof of Reserve attestation where you hold balances, so backing is provable on-chain.

02

How an engagement works

1

Scope & design

A payment-flow review that maps the rails you need (ramp, settlement, cards, treasury), the compliance and custody model, and the providers to integrate, into an architecture your compliance and finance teams can sign off. Deliverable: a scoped architecture and integration plan.
2

Build & integrate

The settlement contracts and payment logic, the ramp, card, and custody integrations, and the treasury and reconciliation layer, built, integrated with your chosen providers, and tested end to end.
3

Launch & operate

Rollout under your brand, with the contracts hardened ahead of an external audit, and an option to keep us on for 24/7 managed operations, monitoring, and reconciliation once it is live.
03

What teams build crypto payments for

Accepting or settling payments in stablecoins
On/off-ramp between fiat and stablecoins
Non-custodial card payments for users
Cross-border settlement on stablecoin rails
Treasury, FX, and reconciliation for on-chain flows
Compliance and custody built into the payment flow
04

Payment rails we run in production

Protofire is a blockchain development company with 250+ projects across 60+ networks since 2016, and payments sit on infrastructure we already build and operate. We build cross-border stablecoin settlement into products, with issuer and on/off-ramp orchestration, treasury and reconciliation, and Chainlink CCIP cross-chain settlement.

We built the DEX core and subgraph for Swarm, a BaFin-licensed DEX at launch where only KYC-verified wallets can trade. We are partnering with Wirex to bring non-custodial card payments to blockchain projects, deploying the Wirex BaaS card stack on-chain and integrating Wirex card payments into partner products.

As a core contributor to Chainlink we build the oracle and Proof of Reserve layers a payment system leans on, and we deployed Safe on 120+ EVM networks, where it secures $2B+. We maintain Solhint, the linter used by 1M+ developers, so the contracts moving your users' money start from the standard the ecosystem sets.

When the payer is an AI agent rather than a person, the same rails sit under agentic payments: x402 and MPP paywalls, agent wallets and checkout protocols.

“We build stablecoin settlement, on/off-ramp, and non-custodial card payments, under your own brand.”

FAQ

What is crypto payment gateway development?
Crypto payment development is building the system that moves money on-chain end to end: bringing users in from fiat through an on-ramp, settling value in a stablecoin, keeping balances and books reconciled, enforcing compliance, holding funds under a custody model you trust, and letting users spend what they hold. Most of the engineering is in the rails on either side of the stablecoin transfer. A payment gateway specifically is the layer that accepts and routes payments, but a real product also needs treasury, reconciliation, compliance, and often card spending around it. Protofire builds these as production systems, drawing on stablecoin settlement rails we already run and a Wirex partnership for card payments, rather than assembling a demo.
Do you build stablecoin payment rails?
Yes, it is our core strength in payments. We build the flows that accept, hold, and settle value in stablecoins, with multi-issuer support (such as USDC and USDT), cross-chain settlement through Chainlink CCIP, and the treasury and reconciliation that keep balances correct across chains and currencies. We build cross-border stablecoin settlement into products under the client's own brand, including issuer and on/off-ramp orchestration. Because we are a core contributor to Chainlink, the oracle, cross-chain, and Proof-of-Reserve pieces that payment rails depend on are built in-house rather than integrated blind. Stablecoin settlement is the part of a payment product where we have the deepest production track record.
Can you add fiat on-ramp and off-ramp?
Yes. The fiat edge is usually the hardest part of a payment product, and we build it by orchestrating the on and off ramps between fiat and stablecoins, integrating the ramp and PSP providers you choose rather than locking you into a single vendor. KYC is enforced at the point of entry, and we built the DEX core for Swarm Markets, a BaFin-licensed DEX at launch where only KYC-verified wallets can trade, so regulated venues are familiar ground for us. We scope which providers fit your regions, currencies, and licensing, and build the orchestration and reconciliation that make the ramp reliable, rather than treating it as a single third-party button.
Do you build card payments?
Yes. We are partnering with Wirex to bring non-custodial card payments to blockchain projects. The partnership runs on two tracks: deploying Wirex's BaaS card infrastructure on-chain for networks that need it, and integrating Wirex card payment solutions into other teams' products. The point of non-custodial cards is that a user can spend what they hold without handing custody to a middleman. Wirex is one of the earliest crypto card issuers and operates on the major card networks, so this pairs a proven card stack with the on-chain engineering we do. We scope card work as an integration or deployment engagement rather than a card-issuing license of our own.
How do you handle compliance and custody in a payment system?
By building both into the rails rather than around them. We wire KYC, AML, and Travel Rule checks into the payment flow and enforce them in code, integrating the screening and identity providers you already use. For custody we integrate Safe multisig or an MPC custodian such as Fireblocks so funds are held to your risk model, without us ever taking custody ourselves, and we build Proof-of-Reserve attestation where you hold balances so backing is provable on-chain. This is the same compliance and custody engineering we deliver for regulated venues and stablecoin issuers, applied to the payment flow, so an ineligible transaction is blocked before it settles.
Which stablecoins and chains do you support?
We build multi-issuer and multi-chain by default, rather than tying you to one. On stablecoins that means the major issuers such as USDC and USDT, and the ability to add others as your regions and partners require. On chains it means any EVM-compatible network plus selected non-EVM ones; we have shipped across 60+ networks and deployed Safe on 120+ EVM networks, where it secures $2B+. Cross-chain settlement is handled through Chainlink CCIP so value can move between the chains your users and counterparties are on. The right combination is driven by where your liquidity, your ramps, and your counterparties actually sit, which we scope with you in the design phase rather than assuming a single default.

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Tell us what you are building. An engineer reads it, we have a short call, and the written proposal follows within one business day.

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