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API Development Services That Contract Before They Connect

BigOhTech is an API Integration Development Company that builds Custom API Development Services with versioned contracts, auth, and failure modes. Start with a 40-hour free pilot on one integration KPI before a long SOW.
OpenAPI contracts your teams can test against
Auth and rate limits designed in - not bolted on
Failure modes and retries ops can actually run
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300+Successful Projects
300+
Successful Projects

3,200+Satisfied Clients
3,200+
Satisfied Clients

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4.6/5 | 18k+ Happy reviews
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Clutch Reviews
4.6/5 | 18k+ Happy reviews

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Clutch Reviews
4.6/5 | 18k+ Happy reviews
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Clutch Reviews
4.6/5 | 18k+ Happy reviews

300+Successful Projects
300+
Successful Projects


3,200+Satisfied Clients
3,200+
Satisfied Clients

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Custom API Development Services and Integration Offerings

These are the API Development Services we sell. Each one is scoped to reduce sync risk before partner and system traffic grows.

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API Consulting and API-First Architecture

Decide boundaries, ownership, and versioning before endpoints multiply.
  • Target-state map for internal vs partner APIs
  • Trade-offs on REST, GraphQL, events, and legacy bridges

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Custom API Development Services

Build APIs that encode your business logic - not thin wrappers around a database.
  • Contract-first design with OpenAPI or equivalent specs
  • Vertical slices with acceptance tests on each release

Icon representing Third-Party and Partner API Integration

Third-Party and Partner API Integration

Connect payment, CRM, ERP, shipping, and SaaS vendors with governed access.
  • Sandboxes and credential hygiene for partner environments
  • Mapping and retry rules that survive vendor quirks

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Microservices and Internal API Platforms

Stand up internal APIs so squads share data without copy-paste integrations.
  • Service contracts and ownership clear to consumers
  • Consistent auth and observability across services

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API Security, Testing, and Hardening

Prove auth, abuse controls, and regression coverage before production traffic.
  • Token-based auth, rate limits, and threat-focused tests
  • Evidence packs for security and compliance reviews

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API Lifecycle, Versioning, and Documentation

Keep consumers shipping when you change contracts.
  • Deprecation and version policies teams can follow
  • Docs and examples that match running behavior

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API Monitoring, Support, and Continuous Improvement

Watch latency, errors, and partner impact after go-live.
  • Alerts tied to SLOs your owners care about
  • Path into IT Support and Maintenance when traffic and consumers grow

CASE STUDY · ENERGY TRADINGIGX: Real-Time Exchange Integrations on FIX and Kafka

We built the exchange portal and trading workstation with integration fabric for Spot and Auction flows - including FIX-aligned messaging and Kafka-backed updates.

The platform handled a published daily trading volume of 1.6 lakh MMBTU with a zero-downtime migration from the prior system.

Read Full Case Study
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APIs You Can Contract-Test - Not Glue Scripts

Connector catalogs hide failure modes. Our Custom API Integration Service work starts with contracts, auth, and a pilot KPI before traffic scales.

Contract-first design - Consumers get specs and examples that match running behavior - not tribal knowledge.
Failure modes designed in - Retries, idempotency, and dead-letter paths are part of the blueprint - not a postmortem.
Pilot before partner scale - You prove latency, error rate, or sync freshness on one slice before wide rollout.
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Why Choose BigOhTech as Your API Integration Development Company

API work fails when undocumented endpoints hit production. Here is how we keep API Development Services tied to contracts ops can run.

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Pilot before the integration SOW

You pick one KPI - latency, error rate, or sync freshness - and we prove it in a 40-hour free pilot. You expand only when the slice earns trust.

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Custom APIs on your business logic

We build Custom API Development Services that encode your rules - not thin CRUD wrappers or marketplace connectors alone.

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Process and delivery posture

Work runs under CMMI Level 3 appraised and ISO 27001 certified practices. Change and access habits match enterprise review.

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Security and abuse controls early

Auth, rate limits, and logging land in the design. Reviews get evidence - not a promise to "secure later."

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Support after partners connect

Monitoring and fixes continue after go-live. You get a clear path into ongoing support when traffic and consumers grow.

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Ready to prove one integration KPI without a year-long glue project?
Start Your 40-Hour Pilot

API Development Services Tailored to Your Industry

Integration constraints differ by industry. We apply Custom API Integration Service patterns to compliance, partner, and volume realities your systems already live with.

View All Industries
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FinTech

  • Payment gateway APIs
  • Ledger sync contracts
  • KYC vendor integrations
  • Audit-friendly logging
  • Rate limits for abuse

Learn More
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Healthcare

  • EHR/EMR bridges
  • PHI-aware access
  • Claims document APIs
  • Partner clinic portals
  • Audit trail hooks

Learn More
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Manufacturing

  • ERP adjacency APIs
  • Dealer portal contracts
  • Supplier data sync
  • Quality record hooks
  • Plant change windows

Learn More
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Retail & E-Commerce

  • OMS and inventory sync
  • Payment and refund APIs
  • Shipping carrier hooks
  • Marketplace connectors
  • Peak-season throttling

Learn More
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Logistics

  • Carrier and EDI bridges
  • Tracking event APIs
  • Partner portal contracts
  • Exception webhooks
  • Control-tower feeds

Learn More
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Travel & Hospitality

  • Booking partner APIs
  • Inventory availability sync
  • Payment and refund flows
  • Disruption webhooks
  • Multi-currency contracts

Learn More
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Automotive

  • Dealer system APIs
  • Parts catalog sync
  • OEM partner contracts
  • Warranty data hooks
  • Service ticket APIs

Learn More
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Media & Entertainment

  • Subscriber billing APIs
  • Content partner feeds
  • Rights metadata sync
  • CDN/origin hooks
  • Analytics event streams

Learn More
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Need API Integration shaped to your vertical?
Schedule a Technical Discussion

Our API Development Services Delivery Process

Each step ends with a result you can score - contracts, tests, or observed KPIs - so integrations do not drift into undocumented glue.

01

Frame integration outcomes and contracts

We lock consumers, SLOs, and the one KPI the first slice must move. Result: Written outcome, contract scope, and success criteria sponsors can approve.

02

Assess systems and auth constraints

We map systems, identity, data ownership, and vendor quirks that break naive connectors. Result: Feasibility pack with go/no-go flags - not a vague opportunity list.

03

Design API and integration blueprint

We define styles, versioning, security, and failure modes before code volume grows. Result: Blueprint and OpenAPI (or equivalent) draft your architects can review.

04

Build and contract-test a thin slice

Teams ship endpoints and integrations against acceptance tests in your tools. Result: Demoable slice consumers can call in a sandbox.

05

Harden security, load, and failure modes

We prove auth, rate limits, retries, and error contracts under realistic traffic. Result: Go/no-go evidence - not a slide saying "secure."

06

Launch, observe, and hand off

We stabilize production traffic and hand off operate habits or ongoing support. Result: Clear ownership path, including IT Support and Maintenance when needed.

Choose the Right Custom API Integration Service Model

Pricing stays Custom because system count, auth, and partner depth differ. What stays fixed: quality meaning, time-to-start, and a low-risk pilot path. Senior engineers who write contracts and failure modes - not junior-only connector wiring. Domain screens happen before names land on the SOW. A scoped 40-hour free pilot can start after a short discovery call. Broader programs begin once KPI, systems, and team shape are agreed.

API Pilot

Best when you need expand/stop evidence before a long integration SOW.

Custom
One integration KPIContract draft + thin slice on a ~40-hour free pilot path
Start Here
Pilot
One integration KPI · ~40-hour free pilot path
Custom APIs
Contract draft + thin slice
Security
Clear expand/stop decision
API Program
Most Popular

Best when you need a delivery lead in your tools across a scoped program.

Custom
Quote after discoveryCustom APIs + partner integrations
Get Pre-Vetted Profiles
Custom APIs
Custom APIs + partner integrations
Security
Security and contract tests
Process
Delivery lead in your tools
Integration Pod

Best when you need stable multi-quarter API backlog capacity with monitoring habits baked in.

Custom
Multi-quarterVersioning and consumer support
Talk To Sales
Support
Monitoring + support path
Custom APIs
Versioning and consumer support
Pilot
Multi-quarter API backlog

Outcomes from Integration-Led Deliveries

These figures come from published BigOhTech portfolio and case study pages. We do not invent uptime percentages for this API Development Services page.

View All Case Studies
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Case Study
IGX
1.6 lakhMMBTU daily trading volume


FIX + KafkaMessaging fabric on delivery stack

Why Businesses Choose BigOhTech for API Development Services

Freelance integrators and DIY/iPaaS-only approaches both struggle when contracts, auth, and failure modes must stay operable. Here is how a custom API partner compares.

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Time to first contract-tested slice
Custom business logic APIs
Failure modes & retries
Process & security posture
Data & IP protection
Cost clarity
Recommended
BIgOH Logo
green check
Pilot-scoped after discovery
green check
Custom API Development Services
green check
Designed into blueprint
green check
CMMI L3 / ISO 27001 habits
green check
Client IP under MSA/SOW + NDA
green check
Custom quote + quality meaning + pilot
Time to first contract-tested slice
Custom business logic APIs
Failure modes & retries
Process & security posture
Data & IP protection
Cost clarity
Freelance integrator
red check
Varies
red check
Ticket-only
red check
Often undocumented
yellow check
Vendor-dependent
yellow check
Contract-dependent
red check
Hourly surprises
Recommended
BIgOH Logo
green check
Pilot-scoped after discovery
green check
Custom API Development Services
green check
Designed into blueprint
green check
CMMI L3 / ISO 27001 habits
green check
Client IP under MSA/SOW + NDA
green check
Custom quote + quality meaning + pilot
DIY / iPaaS-only
red check
Tool-limited
red check
Connector catalog
red check
Vendor defaults
yellow check
You assemble evidence
yellow check
Platform terms
red check
Seat + hidden eng time

Custom API Integration Service Patterns for Every Need

These use cases are what gets connected - separate from how we package API Development Services above.

Start Your Project
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ERP and CRM data sync APIs

Keep customer and order data aligned across ERP and CRM without nightly spreadsheet glue.

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Payment and billing API integration

Connect gateways and billing systems with idempotent charges, refunds, and audit-friendly logs.

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Event-driven and webhook architectures

Push real-time updates with retries and dead-letter paths when partners cannot poll reliably.

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Legacy SOAP to modern REST/GraphQL bridges

Wrap or replace brittle legacy interfaces without a reckless big-bang cutover.

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Partner / B2B API programs

Expose partner APIs with sandboxes, keys, and rate limits so ecosystems can integrate safely.

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Internal microservices API platforms

Standardize internal contracts so squads share data without copy-paste integrations.

Technologies Behind Our API Development Services

We pick protocols and tools that fit your consumers and operate habits - not a logo parade.

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REST
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gRPC
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GraphQL
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OpenAPI
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SOAP
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Webhooks
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OAuth 2.0
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AsyncAPI
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Java
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C# / .NET
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TypeScript
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Python
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Node.js
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AWS API Gateway
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Kotlin
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Go
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PHP
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Azure APIM
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Kong
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Google Cloud
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Cloudflare
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PostgreSQL
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Docker
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Kubernetes
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NGINX
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MongoDB
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Redis
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MySQL
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Kafka
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FIX
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Elasticsearch
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RabbitMQ

Our Strategic Industry Partnerships

We have decades of experience in emerging technology and engineering that help businesses to quickly ramp the tech team at an affordable cost.  

AWS logo
AWS
Google cloud
Google cloud
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Shopify
Slack
Slack
Open AI logo
Open AI
Microsoft Azure
Microsoft Azure
Meta logo
Meta
Zendesk logo
Zendesk
Salesforce
Salesforce
HubSpot
HubSpot
Industry InsightsAPI Development Services That Reduce Sync Risk Before Partners Scale

We build Custom API Development Services with contracts, auth, and failure modes your consumers and ops teams can run in production. Still connecting systems with undocumented scripts and hope?

Industry integration guides still stress contract-first design and versioning before traffic grows - we force OpenAPI-style specs and contract tests before partner scale.
APIs need operate ownership after go-live - we connect handoff to a real IT Support and Maintenance path so consumers are not left with silent breakage.
See How We Work
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Capabilities That Power API Integration Development

These capabilities explain how we deliver as an API Integration Development Company - not logo tiles.

Discuss Your Stack
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Event and webhook delivery

Push updates with observability when polling cannot meet freshness needs.

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Auth and access control

OAuth, JWT, API keys, and role rules designed for real consumer classes.

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API security testing

Abuse, auth, and regression checks before production traffic.

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Contract-first API design

Specs, examples, and ownership land before consumers depend on tribal knowledge.

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Resilience patterns

Retries, idempotency, timeouts, and dead-letter paths for flaky partners.

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Observability and SLOs

Latency, error, and saturation signals tied to owners who can act.

Why our clients love working with us

View All Reviews
Clutch review

Our awards and accolades validate our work; we are the best application development company in India & USA.
MA
Michael Anderson
VP of Product
2 days ago
The team understood our requirements quickly and turned a complex idea into a practical AI solution. Communication was smooth, and they stayed focused on delivering quality.
SM
Sarah Mitchell
Founder & CEO
2 days ago
We came in with an early AI idea and needed something we could actually put in front of users. The team helped us turn it into a working product quickly and were very hands-on throughout the process.
DC
Daniel Carter
Director of Technology
2 days ago
Integrating AI into our existing systems could have been complicated, but the team made the process fairly straightforward. They were responsive whenever we had questions and kept things moving.

Insights, Guides & Success Stories

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10 Mins Read • 15 April 2024
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10 Mins Read • 5 July 2023
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10 Mins Read • 30 September 2025

Frequently Asked Questions (FAQs)

Why choose BigOhTech as an API Integration Development Company?

You get pilot-first delivery, contract-tested APIs, and failure modes designed in - not undocumented glue. We deliver under CMMI Level 3 appraised and ISO 27001 certified process.


Do you build REST, GraphQL, gRPC, and SOAP bridges?

Yes. We choose styles based on consumer needs and legacy constraints. Bridges to SOAP or other legacy protocols are designed with versioning and cutover plans - not a reckless rewrite.


How is Custom API Integration Service pricing structured?

Pricing is Custom because system count, auth, and partner depth differ. We share quality meaning, time-to-start, and a model (pilot, program, or integration pod) before you commit.


How do you secure APIs during development and integration?

Auth, encryption in transit, rate limits, and logging are designed into the blueprint. We harden with targeted security and regression tests before production traffic.


How long until a first API slice can start?

A scoped pilot can start after a short discovery call once KPI and systems are clear. Multi-system partner programs take longer when auth and compliance are heavy.


What is in scope for API Development Services?

Typical scope covers API consulting, Custom API Development Services, third-party and partner integrations, microservices APIs, security testing, versioning/docs, and monitoring. First pilots usually own one KPI such as latency, error rate, or sync freshness.


What maintenance and support plan do you offer after APIs go live?

We offer monitoring, incident response, and contract updates as consumers and vendors change. See our IT Support and Maintenance service for ongoing ownership options.


How is this different from buying an iPaaS connector pack?

Connectors help when they fit. We build Custom API Development Services for your business logic, edge cases, and operate needs - then use platforms only where they earn their place.


Can you integrate payment, ERP, CRM, and shipping APIs?

Yes. Third-party and partner integrations are a core Custom API Integration Service pattern, with sandboxes, mapping, and retry rules that survive vendor quirks.


How does the 40-hour free pilot work for API work?

We pick one integration KPI and one thin slice, then prove readiness inside about 40 free hours. You decide whether to expand without a long SOW first.


Who owns IP, specs, and source code?

Your IP, repos, and API specs stay yours under the MSA and SOW. We work under NDA for architecture and data discussions.


How do you handle API versioning when consumers are live?

We define version and deprecation policies up front and keep docs aligned with running behavior. Breaking changes require an agreed consumer path - not silent field renames.

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Keep APIs and integrations healthy after launch with monitoring and fixes.
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Custom Software Development

Turn API contracts into product surfaces and workflows on your stack.
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Transform Your Vision into Reality

Share your business goals, timeline, and technical requirements. Our experts will review your needs and provide a tailored solution with an indicative estimate within 48 business hours.

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Build Enterprise Systems That Scale With Your BusinessFrom complex enterprise platforms to mission-critical applications, we engineer secure, scalable, and future-ready solutions tailored to your business goals. Let's discuss how we can help accelerate your digital transformation.
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