YOUR SENIOR TECHNICAL PARTNER FOR SUBSCRIPTION BILLING & API INTEGRATION
I'm Ajeet Kumar. I build custom subscription billing systems and reliable API integrations for recurring payments — Stripe, Authorize.Net, PayPal, HubSpot — for SaaS founders and ecommerce teams who have outgrown the limits of an off-the-shelf billing software.
What You Get
A subscription billing system that fits your pricing, not the other way around
Recurring billing that recovers revenue instead of quietly losing it
API integration that keeps your product, CRM and books in agreement
A billing software layer that survives switching or adding a payment processing provider
When SaaS Billing Becomes the Bottleneck
Most SaaS billing starts with a hosted checkout. It works until your pricing gets interesting — usage tiers, annual discounts, mid-cycle upgrades, coupons, multi-currency, an enterprise deal that needs invoicing. Suddenly your billing software is fighting your product roadmap.
This is where custom subscription billing and proper API integration stop being a nice-to-have and start being the thing your revenue depends on.
What I Build
Subscription Billing & API Integration Done Right
Custom billing software, recurring billing automation, and payment processing integration built the way SaaS revenue systems need — accurate, observable, and safe to change.
How I Build It
I Design for the Failure Paths First
Recurring billing failures are silent. A subscription that quietly stops renewing looks exactly like a customer who lost interest. By the time anyone notices, the revenue is already gone — and the customer relationship with it. So I design for the failure paths first.
Who I Work With
SaaS & Ecommerce Teams Who Have Outgrown Off-the-Shelf Billing
SaaS founders whose billing model has outgrown a hosted-checkout tool
Ecommerce and DTC teams launching subscription tiers, bundles, or memberships
CTOs handling multiple currencies, providers, or geographies
Founders who could build this themselves but want engineering time going into the product
Teams that have discovered SaaS billing contains more edge cases than the documentation suggests
How I Work
Working Software, Not Proposals
Phased Delivery
A scoped first phase — small, independently useful, delivered quickly. You judge working software rather than a proposal, then decide on the next phase.
Honest Scoping
If an existing connector or no-code tool covers part of what you need, I'll tell you. Custom work is for the parts where accuracy and edge cases genuinely have to be guaranteed.
You Own What I Build
Hosting sits in your account. Documentation is written so another developer can pick it up. I build subscription billing systems clients can maintain, not dependencies on me.
Direct Senior Attention
You work directly with me — the engineer building your integration — not an account manager relaying messages to a junior team.
Experience
17+ Years Building Billing & Integration Systems
For clients across the US, UK, Europe and Australia. My work spans subscription billing, recurring billing automation, payment processing on Stripe, Authorize.Net and PayPal, WooCommerce ecommerce integrations, and API integration with HubSpot and accounting platforms.
17+
Years building billing & backend systems
1,000+
Monthly recurring clients on one build
3+
Gateways: Stripe, Authorize.Net, PayPal
~90%
Admin effort reduced vs manual process
Recent Work
A complete recurring billing infrastructure on Authorize.Net for an agency managing over 1,000 monthly recurring clients — tokenised payments, subscription lifecycle, webhook automation with idempotency, failed-payment recovery, reconciliation, and API integration with HubSpot for consistent customer data.
Replaced a manual process · ~90% less administrative effort
Ready to Fix Your Subscription Billing?
Tell me what your subscription billing setup looks like now and where it hurts. I'll tell you honestly what needs custom work, what an off-the-shelf tool can still handle, and where your current billing software is most likely to fail quietly.
No pitch. If you don't need me, I will say so.