Engineering
Payment, CRM and API Integration Services
Stripe, Razorpay, HubSpot, Salesforce, WhatsApp and the rest of your stack, connected properly and monitored.
What is integrations & api development?
Integration work is the engineering that makes separate systems agree with each other: a payment gateway writing into your accounting system, a website form creating a CRM deal, a messaging platform sending order updates. RegalBit Solutions has shipped production integrations with Stripe, Razorpay, PayPal, HubSpot, Salesforce, Zoho, the WhatsApp Business API, Slack, Shopify, WooCommerce, AWS Cognito and OpenAI, and the engineers who built them are the ones who will build yours.
Integrations fail in ways that ordinary features do not. A button that breaks is obvious. A webhook that silently drops one payment in five hundred is not, and it is discovered by an accountant three months later. That difference shapes how the work has to be done.
So we build for the failure cases first. Idempotency keys so a retried webhook cannot charge twice or duplicate a record. Signature verification on every inbound call. Exponential backoff on rate limits. A reconciliation job that compares both sides on a schedule and reports the difference. Structured logs with a request identifier you can trace end to end. None of that is glamorous and all of it is what separates an integration that runs for years from one that quietly corrupts your data.
Payments are the area we are asked about most. We have built Stripe subscriptions and billing portals, Razorpay checkout with UPI and payouts, PayPal express and recurring flows, and gateway integration inside a geospatial ordering platform with a wallet and points system on top. On the CRM side we have built bidirectional HubSpot and Salesforce sync over REST and webhooks, and automated a full CRM to billing pipeline that removed all manual finance data entry.
The other request that has grown quickly is messaging. The official WhatsApp Business API for reminders, order updates and two way conversational flows, plus Slack bots, Twilio SMS and social platform APIs for publishing and insights.
Deliverables
What we build
Payment gateway integration
Stripe, Razorpay, PayPal. Checkout, subscriptions, refunds, payouts, webhooks, invoicing and a reconciliation report you can trust.
CRM integration
HubSpot, Salesforce and Zoho. Contacts, deals, custom objects and bidirectional sync over REST and webhooks with conflict handling.
WhatsApp Business API
Official API onboarding, message templates, two way conversational flows and delivery status tracking.
Third party and custom APIs
Where no connector exists we build the client: authentication, pagination, rate limiting, retries and a typed contract.
Identity and authentication
AWS Cognito, OAuth and SSO integration for enterprise grade authentication.
Monitoring and reconciliation
Scheduled jobs that compare both systems and alert on divergence, so nobody discovers a gap at the end of a quarter.
Process
How a integrations & api development project runs
Written scope and a fixed quote before anything is built, then visible progress at every stage.
- 1
Map
We document every system involved, what data moves where, which side owns each field, and what has to happen when the two disagree.
- 2
Contract
A written integration specification covering endpoints, payloads, authentication, error handling and the reconciliation rule. Approved before code.
- 3
Build
Developed against sandbox credentials with idempotency, signature verification and retries built in from the first commit.
- 4
Verify
Tested against real edge cases: duplicate webhooks, out of order delivery, rate limits, partial failures and expired credentials.
- 5
Monitor
Logging, alerting and a scheduled reconciliation job go live with the integration, not after the first incident.
Technologies
What we use
Named, specific and current. We list what we have shipped, not what we have read about.
- Stripe
- Razorpay
- PayPal
- HubSpot
- Salesforce
- Zoho
- WhatsApp Business API
- Twilio
- Slack API
- AWS Cognito
- OpenAI API
- Shopify API
- WooCommerce
- Meta Graph API
- Google Workspace APIs
- Webhooks
Who this is for
You will get the most from this if…
Products that need to take money
Subscriptions, marketplaces, wallets or one off checkout, in India or internationally.
Sales teams whose tools do not talk
The website, the CRM and the billing platform each hold a different version of the truth.
Businesses that live on WhatsApp
Your customers message you there, and your systems have no idea it happened.
Engineering rates
What this costs
We publish a rate band rather than a project price, because a project price without a scope is a guess. Once we understand the work we convert it into a fixed written quote, so you carry no open ended risk.
Integrations & API Development
From $12 / hour
Typical band: $12 to $35 per hour
Integration work is quoted from the specification. A single well documented gateway is fast. A legacy system with no API and a CSV export is not, and we will say so before you commit.
Why us
What makes this different from the other quote you are getting
An eight person engineering team, with a dedicated designer and a dedicated tester, shipping production software since 2017. The person who scopes your project is the person who builds it.
- Idempotent by default. A retried webhook cannot charge a customer twice or duplicate a record.
- Every integration ships with a scheduled reconciliation job, so divergence is detected by software rather than by an accountant.
- We have shipped these specific integrations in production, not read the documentation. Stripe, Razorpay, HubSpot, Salesforce, WhatsApp, Cognito, Slack and OpenAI are all live in client systems today.
- Signature verification, rate limit handling and structured request tracing as standard, not as a later hardening project.
Questions
Integrations & API Development, frequently asked questions
Stripe, Razorpay and PayPal most often, covering checkout, subscriptions, refunds, payouts, UPI and webhooks. We have also built gateway integration inside a custom ordering platform with a wallet and points system layered on top. If you use a gateway not on that list, the work is the same shape and we will quote it.
Yes. Bidirectional sync over REST APIs and webhooks, covering contacts, deals, custom objects and lifecycle stages, with conflict handling for the cases where both sides changed. We have built CRM to billing automation that removed manual finance data entry entirely.
Yes, including the official onboarding, message template approval, two way conversational flows and delivery status tracking. We use the official API rather than unofficial libraries, so your number is not at risk.
Then we look at the alternatives honestly: a database level integration, a scheduled file exchange, or in some cases a browser automation of last resort. We will also tell you when the correct answer is to change the software rather than integrate around it.
Idempotency keys on every write, signature verification on every inbound webhook, retry with exponential backoff, and a scheduled reconciliation job that compares both systems and alerts on any difference. That combination is what keeps an integration trustworthy over years.
Integrations & API Development where you are
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Ready to talk about integrations & api development?
A free 30-minute call. We will tell you what is feasible, roughly what it costs, and whether we are the right people for it.
Engineering since 2017 · Clients in 7 countries · Rates from $10 per hour