01
Stripe integration
Stripe Checkout for a fast hosted page, Elements for custom-designed checkouts, Billing for subscriptions and Connect for marketplaces.
FIG 01 · Payment Gateway Integration
Payment gateway integration for websites, apps and SaaS
Stripe, PayPal, Square and Razorpay checkouts, subscriptions and refunds built into your product, with hosted fields or tokenization so card data stays off your servers, and webhooks reconciled into your books.
See how it works
FIG 02 · Quick answer
What is payment gateway integration?
Payment gateway integration connects your website, app or SaaS to a provider like Stripe, PayPal, Square or Razorpay so customers can pay securely. Elgrith picks the right gateway for your markets, builds checkout, subscriptions and refunds, handles webhooks and reconciliation, and keeps card data off your servers to reduce PCI scope.
- Markets we design checkouts for: the US, UK and India
- 3
- Projects delivered since 2015
- 1,000+
- Clients across the USA, UK and India
- 250+
- Your gateway accounts, code and payment data
- 100%
FIG 03 · Why it matters
Checkout pages are a target. The rules moved.
From the PCI Security Standards Council and Stripe Support, read in October 2026.
01
31 Mar 2025
New PCI DSS e-commerce requirements in force
The PCI SSC says the future-dated e-commerce requirements in PCI DSS v4.0.1 became effective “on the 31st of March 2025”. How your checkout is built decides how many apply to you.
Source: PCI Security Standards Council blog, 26 Mar 2025(opens in a new tab)02
Scripts
Payment page scripts are a target
The PCI SSC: “Scripts running in a consumer’s browser are now a significant target for attackers seeking to steal payment card data.” We keep payment pages lean and their scripts accounted for.
Source: PCI Security Standards Council blog, 26 Mar 2025(opens in a new tab)03
2.9% + 30¢
Stripe’s standard US card fee
Stripe Support lists standard card payments at “2.9% + 0.30 USD in the US”. Gateway fees are paid to the provider, not to us, and vary by country and payment method.
Source: Stripe Support, manually entered card payments(opens in a new tab)
FIG 04 · Definitions
Payment gateway vs payment processor vs merchant account
Three roles in every card payment. Providers like Stripe, PayPal, Square and Razorpay bundle them into one account; older setups split them across companies.
| What it does | Who provides it | With Stripe, PayPal, Square or Razorpay | |
|---|---|---|---|
| Payment gateway | Securely captures payment details and passes them on for approval | The provider, or a gateway such as Authorize.Net | Included in your account |
| Payment processor | Routes the transaction through the card networks and back | Processors working with the networks | Included in your account |
| Merchant account (acquirer) | The bank account that receives card funds before payout | An acquiring bank | Handled by the provider; you get payouts |
| Your integration | Checkout, webhooks, refunds and reconciliation in your product | Your developers, or us | What we build |
FIG 05 · What you get
Gateways we integrate
We integrate the gateway that fits your markets, product and existing stack. Your merchant accounts are registered to your business, and we claim no partner status with any provider.
02
PayPal and Venmo
PayPal Checkout with PayPal, Pay Later and Venmo buttons for US buyers, plus Braintree when you need cards and PayPal in one integration.
03
Square
Square online payments for your site or app, with orders, customers and catalog kept in step with Square in-store sales.
04
Razorpay, UPI and Indian gateways
Razorpay, Cashfree or PayU with UPI, cards, net banking and wallets, plus recurring payments and Razorpay Route for split settlements.
05
Apple Pay, Google Pay and buy now, pay later
Wallet buttons and BNPL options such as Klarna and Afterpay, through gateways that support them in your markets.
06
Adyen and Authorize.Net
Integrations for businesses that already have an Adyen account or an Authorize.Net gateway on a bank merchant account.
07
Payment gateway development
A payment layer in your product that routes between gateways by market or currency, with one set of webhooks and reports.
08
Multi-currency and local methods
Prices and checkouts in local currencies, with the payment methods buyers in each market expect.
Deliverables
12
deliverables, in writing
Included in every build, written into your fixed quote before work starts.
FIG 06 · What we build
What we build
From a single pay button to marketplace payouts. Every build includes tested webhooks, refunds and reconciliation, not only the happy path.
- Website
- Mobile app
- SaaS product
- Invoices and links
Payment gateway
- Payouts to your bank
- Accounting
- ERP
- CRM
One-off checkout
- For
- Stores, bookings and digital products
- Built with
- Hosted checkout or embedded fields
- Includes
- Receipts, refunds and order webhooks
Subscriptions and dunning
- For
- SaaS, memberships and boxes
- Built with
- Stripe Billing, PayPal subscriptions or Razorpay Subscriptions
- Includes
- Trials, upgrades, proration and failed-payment retries
Marketplaces and split payments
- For
- Platforms that pay sellers or providers
- Built with
- Stripe Connect or Razorpay Route
- Includes
- Onboarding, payouts and platform fees
Invoices and pay-by-link
- For
- B2B, services and phone orders
- Built with
- Hosted invoices or payment links
- Includes
- Reminders and automatic matching
Refunds and disputes
- For
- Every payment flow
- Built with
- Gateway refund and dispute APIs
- Includes
- Admin tools and evidence collection
Payments in mobile apps
- For
- Physical goods and services sold in apps
- Built with
- Native SDKs, Apple Pay and Google Pay
- Includes
- Saved payment methods as provider tokens
FIG 07 · Flagship build
Proof: one balance across 200+ models
Kenerate AI is our flagship build, an all-in-one AI studio designed and engineered by Elgrith. It isn’t a payments product, but its account model is the kind of billing experience we build: one login and one credit balance across the whole app.
- One login and one credit balance across 200+ AI models
- Credits never expire
- Commercial use, no watermark, up to 4K output
- 1,000+ projects for 250+ clients since 2015
The idea: 15 apps, 15 logins, 15 bills become one studioDesigned and engineered by Elgrith
- AI models in one app
- 200+
- Studios and tools
- 23+
- Maximum output
- 4K
- Guides
- 500+
FIG 08 · Security
Security and compliance
We build to PCI DSS v4.0.1 and, for UK and EU buyers, Strong Customer Authentication. Hosted checkout, hosted fields and tokenization keep card data off your servers and reduce your PCI scope. Your acquirer and your assessor decide your compliance status; this is how we build, not compliance or legal advice.
06principles
Hosted checkout or hosted fields
Card details are typed into the provider’s page or fields, so they don’t pass through your servers and your PCI scope is reduced.
Tokenization
Saved cards and subscriptions use the provider’s tokens rather than card numbers, which also reduces your PCI scope.
Payment page scripts
An inventory of every script on your payment pages, with a Content Security Policy, to support the PCI DSS v4.0.1 e-commerce requirements on payment page scripts.
3-D Secure 2 and SCA
Strong Customer Authentication for UK and EU cards through the gateway’s 3-D Secure 2 flows, with exemptions handled by the gateway.
Fraud tools
The gateway’s fraud screening, such as Stripe Radar, set up with rules and a review queue that fit your risk.
Keys and webhooks
API keys kept in a secrets manager with restricted permissions, and every webhook signature verified.
FIG 09 · After go-live
After go-live: webhooks, reconciliation and reporting
Most payment bugs show up after launch: a missed webhook, a double charge, a payout nobody can match. We build for those from day one.
06principles
Webhooks with idempotency
Every payment event handled once, even when the gateway sends it twice, using idempotency keys and event logs.
Retries and dead letters
Failed events retried, then parked in a queue your team can see and replay.
Reconciliation into your ERP
Payouts matched to orders, refunds and fees, and posted to your ERP or books.
ERP developmentCustomer status in your CRM
Subscription status, failed payments and lifetime value visible to sales and support.
CRM development
FIG 10 · Process · 4 steps
Pick the gateway, then test every edge
A fixed written quote after a free call, sandbox testing of every flow, and a careful switch to live payments.
- Step 01
Discovery
Your markets, currencies, payment methods, products and existing stack, and a gateway recommendation. You get a written scope and a fixed quote.
- Step 02
Build in sandbox
Checkout, subscriptions, refunds and webhooks built against the gateway’s test mode, with weekly demos.
- Step 03
Test every edge
Declines, 3-D Secure challenges, duplicate webhooks, partial refunds and failed renewals tested before launch.
- Step 04
Go live and reconcile
Live keys switched on in accounts registered to your business, first payouts reconciled, and support after launch if agreed in your written scope.
FIG 11 · What you get
Everything included
Written into your fixed quote, so you know exactly what you are paying for before work starts.
12items
- Gateway recommendation for your markets
- Written scope and fixed quote
- Checkout built on hosted checkout or hosted fields
- Subscriptions, invoices or marketplace payouts, as scoped
- Refund and dispute handling
- Webhooks with idempotency and retries
- 3-D Secure 2 for UK and EU cards
- Payment page script inventory
- Reconciliation to your books or ERP
- Sandbox test report for every flow
- Runbook for refunds, disputes and key rotation
- Gateway accounts and code, all yours
FIG 12 · Tech & tools
The tools behind the work
Proven, well-supported tools, chosen for your project and set up in accounts your business owns.
- Stripe Checkout
- Stripe Elements
- Stripe Billing
- Stripe Connect
- PayPal Checkout
- Braintree
- Square
- Adyen
- Authorize.Net
- Razorpay
- Cashfree
- PayU
- UPI
- Apple Pay
- Google Pay
- Klarna
- Afterpay
FIG 13 · Who it’s for
Payments for products that sell.
From a first checkout to multi-market billing.
3 audiences
Stores
A checkout that converts and reconciles.
Custom stores and booking sites with a fast checkout, wallets and BNPL, and payouts that match the orders.
- Hosted checkout or embedded fields
- Apple Pay and Google Pay
- Refunds from your admin
- Payouts reconciled to orders
SaaS
Billing that runs itself.
Plans, trials, upgrades, proration, invoices and dunning, with subscription status in your app and your CRM.
- Stripe Billing or Razorpay Subscriptions
- Self-serve plan changes
- Failed-payment retries and emails
- Revenue and churn reporting
UK and India
Local methods, local rules.
UK checkouts with Strong Customer Authentication through 3-D Secure 2, and Indian checkouts with UPI through Razorpay, Cashfree or PayU.
- SCA-ready UK and EU flows
- UPI, cards and net banking for India
- GBP, EUR, USD and INR pricing
- One integration layer if you sell in several
FIG 14 · Working with us from the USA and UK
Built in New Delhi. Run on your hours.
Every project gets a point of contact in New York or London and an engineering team in New Delhi. Here is how today’s working days line up, live.
New York
North America
--:--ET
New Delhi team Your working day- Shared working time
- ≈ 3 hours today
- New Delhi is
- 10.5 h ahead
- Live calls, your time
- 9 a.m. to 12 p.m. ET
London
UK & Europe
--:--UK
New Delhi team Your working day- Shared working time
- ≈ 4.5 hours today
- New Delhi is
- 5.5 h ahead
- Live calls, your time
- 9 a.m. to 1:30 p.m. UK
Three ways to work together
- 01
Fixed-scope project
A written scope, one fixed price and a dated plan. Suits websites, apps and MVPs.
- 02
Dedicated team
Designers and engineers on your roadmap every month, billed monthly.
- 03
White label
For US and UK agencies: our work, your brand, unbranded deliverables.
Every engagement
- Fixed quote in USD, GBP or INR after a free 30-minute call
- NDA before discovery. You own all code, designs and content
- A working demo every sprint, not status slides
- Reply within one business day, calls inside your hours
Book a call
Calls on ET or UK hours
FIG 15 · Decide
Choosing a gateway for the US, UK and India
A short list by market. The final choice depends on your product, payment methods and fees, which each provider publishes on its own pricing page.
| US | UK | India | |
|---|---|---|---|
| Common choices | Stripe, PayPal, Square, Authorize.Net | Stripe, PayPal, Square, Adyen | Razorpay, Cashfree, PayU |
| Methods buyers expect | Cards, Apple Pay, Google Pay, PayPal and Venmo | Cards, Apple Pay, Google Pay, PayPal, BNPL | UPI, cards, net banking and wallets |
| Rules to design for | PCI DSS | PCI DSS, plus SCA and 3-D Secure 2 | PCI DSS, plus RBI rules for saved cards and recurring payments |
| Fees | Stripe Support lists 2.9% + 0.30 USD for standard US card payments | See each provider’s UK pricing page | See each provider’s pricing page |
Fees change and depend on your volume, card mix and payment methods. Check each provider’s own pricing page before you choose; we help you compare.
Read Stripe vs PayPal vs Square (2026)FIG 16 · Checklist
Payment integration services: how to choose a developer
Most payment integration services can make a test payment work. These questions show who will still be there when live payments get messy.
| Ask for | Why it matters | What good looks like |
|---|---|---|
| Their PCI approach | A custom card form widens your scope | Hosted checkout or hosted fields by default |
| Webhook handling | Missed or duplicate events cause lost or double orders | Idempotency keys, retries and an event log |
| Edge-case testing | Declines and 3-D Secure challenges happen daily | A test report covering failures, not only success |
| Reconciliation | Finance has to match payouts to orders | Payouts posted to your books or ERP |
| Account ownership | Your money and customer data | Gateway accounts registered to your business |
| No card numbers in logs | Logs are a common leak | Only provider tokens and IDs are stored |
FIG 17 · Compare
Hosted checkout, embedded fields or your own card form?
| Hosted checkout page | Embedded hosted fields | Your own card form | |
|---|---|---|---|
| How it works | Buyers pay on the provider’s page, then return | The provider’s fields sit inside your page | Your page collects card details itself |
| Card data on your servers | No | No | Yes |
| PCI scope | Reduced the most | Reduced, but your payment page scripts matter | Widest |
| Design control | Branding options only | Full control of the page around the fields | Full |
| Best for | Fast launches and most stores | Custom-designed checkouts and SaaS | Rarely worth it; we don’t recommend it |
FAQ
Frequently asked questions
Straight answers about Payment Gateway Integration with Elgrith.
It depends on the gateways and payment methods, whether you need one-off payments, subscriptions or marketplace payouts, the number of markets and currencies, and the systems to reconcile into, such as accounting or an ERP. We don’t publish prices: after a free call you get a written scope and a fixed quote. Gateway fees are paid to the provider.
FIG 18 · Related
Keep exploring
Accounting Software Integration
QuickBooks, Xero, Sage & Tally syncFintech App Development
Banking, payments & open banking appsAPI Integration
Connect your apps, CRM & paymentsE-commerce Development
Shopify, Plus & headless storesSaaS Development
Multi-tenant apps, billing & AIERP Development
Custom ERP & ERP integrationsApp Development
iOS, Android & cross-platformCRM Development
Custom CRMs & HubSpot/Zoho setups
Free 30-minute call
Get paid without the payment bugs.
Tell us what you sell and where. After a free call you get a gateway recommendation, a written scope and a fixed quote.
Pick a day for your call
OpenPick a day. You'll choose a time in your own time zone on the next step.