API Integration & Webhook Engineering
Connect your business platforms into a unified automated pipeline. We engineer fault-tolerant API integrations, secure webhook listeners with HMAC-SHA256 signature verification, idempotency controls, and automated two-way synchronization between CRMs, payment gateways, and internal databases.
Inside Fault-Tolerant Webhook Handlers
Select an integration scenario below to inspect how DevJuni handles incoming API events with cryptographic signature verification and idempotency locks.
Payment Gateway Webhook with HMAC-SHA256 Verification
The 4 Safeguards of Fault-Tolerant APIs
Amateur webhook integrations drop events and double-bill customers. Our architecture guarantees cryptographic trust and zero dropped messages.
HMAC-SHA256 Signature Verification
Incoming payloads are cryptographically checked against shared secrets to ensure the request originated from the authentic third-party provider and was not altered in transit.
Strict Idempotency Key Processing
Every event stores a unique transaction key in a distributed Redis/PostgreSQL cache. Duplicate retries from network glitches are detected and processed exactly once.
Resilient Exponential Backoff Queues
If your CRM or downstream database experiences temporary downtime, incoming webhook events are safely queued and retried with increasing intervals without dropping records.
Token Bucket Rate Limiting
Endpoints are shielded with token bucket rate limiters to protect your infrastructure against brute-force DDoS floods while permitting legitimate burst traffic.
Supported Business Integration Ecosystem
We build native, secure bridges between the tools your team relies upon to run commercial operations.
HubSpot, Zoho CRM, Salesforce, Pipedrive
Automatically capture inbound leads, update contact lifecycles, and sync deal stages directly from website interactions.
WhatsApp Business Cloud API, Twilio SMS, SendGrid
Trigger real-time transaction receipts, booking confirmations, dispatch alerts, and executive phone notifications.
Stripe, JazzCash, EasyPaisa, QuickBooks Online
Process online retainer payments, handle subscription renewals, and generate downloadable tax invoices automatically.
PostgreSQL, Supabase, AWS S3, Google Sheets API
Sync customer manifests, store signed delivery PDF documents, and expose private REST/GraphQL data endpoints.
Exact Engineering Deliverables Included
Every integration is deployed with automated testing, error alerts, and full source code ownership.
Cryptographic Webhook Handlers (HMAC-SHA256)
Secure endpoint receivers that cryptographically verify incoming payloads to prevent spoofing and unauthorized replay attacks.
Idempotent Transaction Processing
Unique idempotency key tracking ensuring duplicate network webhooks never trigger double charges or duplicate order entries.
Resilient Retry Queues & Dead-Letter Handling
Automated exponential backoff retries with dead-letter queue inspection so no customer event is ever lost during outages.
Two-Way CRM & Database Synchronization
Real-time data synchronization between HubSpot, Zoho, Salesforce, Google Sheets, and PostgreSQL databases.
WhatsApp Cloud API Integration
Automated transactional WhatsApp messages for booking confirmations, tracking alerts, and quote inquiries.
Transparent, Requirement-Driven Integration Scoping
API integration projects are scoped based on the number of external software services, webhook event volume, and data transformation complexity.
Frequently Asked Questions
What happens if a third-party API goes down temporarily?
Our integration architecture incorporates resilient message queues with exponential backoff retries. When an external service experiences downtime, incoming events are securely buffered and re-attempted automatically once service is restored, preventing any data loss.
How do you secure webhooks from malicious attackers?
We implement strict HMAC-SHA256 cryptographic signature verification, validate timestamp freshness to defeat replay attacks, and enforce IP allowlists and rate limits so only verified external services can submit events.
Can you integrate our website forms directly with our CRM and WhatsApp?
Yes. We can configure website form submissions to simultaneously notify your sales team via WhatsApp, record the new contact in your CRM (HubSpot, Zoho, etc.), and send an automated email confirmation to the client in milliseconds.
Do we need to pay ongoing fees for custom API integrations?
No. Once our custom integration code is deployed to your infrastructure or serverless runtime, you own the code outright with zero intermediary SaaS subscription markup.