Payments engineering · powered by NUMBER

Payments infrastructure, built by the people who ship it.

Seijak moves established SaaS platforms and high-volume merchants onto payments that actually get supported — engineered on NUMBER's rails, with three decades of processing depth behind every integration.

Talk to an engineer → See how it works
charge.js 
// one integration, fully supported
const charge = await seijak.payments.create({
  amount: 4200,
  currency: "usd",
  source: token,
  "metadata": { platform: "your-saas" }
});
// → settled on NUMBER, reported in real time
FOR ISVs & SaaS

Monetize payments without babysitting your provider.

Embed a gateway and API built for platforms — white-label ready, revenue-share transparent, with developers who actually answer when you call.

Explore ISV solutions →
FOR MERCHANTS

Countertop and virtual terminal, with support that picks up.

Stand-alone processing for mature, high-volume businesses tired of being a ticket number at the big players.

Explore merchant services →
What we run
01

Gateway & API

REST API and hosted fields for platform-grade integrations.

02

Recurring & Invoicing

Card-on-file, subscriptions and text-to-pay built in.

03

Countertop POS

Standalone terminals for in-person, no platform required.

04

Virtual Terminal

Take card-not-present payments from any browser.

Developers talking to developers — not a support queue.

Seijak is CIO-level payments engineering. We've architected onboarding, reporting, risk and end-to-end processing for ISOs, acquirers and national retailers. When the platform-first giants go quiet, we're the partner that answers with an engineer, not a chatbot.

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Consultative by default
Solution design before code — onboarding, reporting, risk.
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Transparent economics
Our costs are your costs. No mystery revenue share.
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Backed by NUMBER
A registered PayFac processing since 1996.
POWERED BYNUMBER — Seijak's payments partner

Three decades of payments, one accountable partner.

NUMBER was founded in 1996 by Visa USA executives and pioneered embedded payments across enterprise platforms. Seijak brings that infrastructure to platforms and merchants who need a real engineering partner.

30yrs
ON THE RAILS

Who we work best with

Established SaaS platforms

Mature products with real transaction volume that aren't yet monetizing payments — or are stuck with a provider that treats them like a startup.

High-volume, low-risk merchants

Seasoned businesses running meaningful monthly volume who are underserved on support and want processing that just works.

Let's talk about your payments.

Tell us where payments live in your business today. We'll bring the engineering.

Contact sales →