API development · Three Index
APIs and integrations that don't break.
REST and GraphQL APIs, webhooks and third-party integrations designed for versioning, observability and the failure modes vendors actually have.
- Team
- 50+ IT professionals
- Delivery
- Design, build, release, support
- Engagement
- Project or dedicated team
What this covers
Concrete work we take on under api development — not a catalogue of buzzwords.
Payment, CRM, EHR, logistics and accounting integrations
Webhook systems and event-driven sync
API documentation and partner onboarding
Problems we take on
If one of these sounds familiar, we have likely shipped something close — and we will say so if we have not.
Systems do not talk to each other without manual CSV work.
An integration fails silently when a vendor changes a field.
Partners need a stable API and you do not have one.
Who this is for
This is for teams whose product has to exchange data with another system, or whose partners are waiting on an API that does not exist yet. The buyer has usually been moving files by hand or discovering that an integration died when a vendor renamed a field.
Vendor access is often the real constraint. If the other party has no API and no documented exchange format, we will say that at the start, because software cannot invent a door the vendor will not open.
How an engagement starts
Written scope
The scope names the callers, the resources, the auth, the version policy, and the failure each integration is allowed to have. Partner APIs include who supports the consumer and what a breaking change requires.
First increment
The first increment is one resource or one vendor path in staging, with a contract (OpenAPI or equivalent), a retry or idempotency rule, and a log you can read when the other side times out. Documentation is written for the person who will call it.
Decisions we make with you
REST is the default when callers are known, caches and gateways matter, and the resource model is stable.
GraphQL fits when many clients need different slices of the same graph and you will own the query cost.
Synchronous calls fit short, reliable operations. A queue fits anything a vendor can fail, throttle, or deliver twice. Silent success on a failed sync is the failure mode we design out of the system.
What you own
You own the API code, the contract, the credentials for each vendor, and the environment it runs in. Versioning and a changelog travel with the contract so partners are not surprised by a field change.
- You own
- API code
- You own
- Contract
- You own
- Credentials for each vendor
- You own
- Environment it runs in
Where this shows up
Integrations carry the weight in clinical systems, where an EHR or a results feed is the product’s source of truth, and in ordering, where payments and fulfilment are separate systems that must agree.
Further reading
API design for partner integrations that do not wake you at night
Versioning, failure, and partner onboarding.
ReadHealthcare software beyond the chart UI
Where those integrations meet clinical workflows.
ReadTechnologies
Stacks we use when they fit the product and your team — not a mandatory toolkit for every engagement.
- Stack
- Node.js
- Stack
- Python
- Stack
- GraphQL
- Stack
- REST
- Stack
- OpenAPI
- Stack
- Queues
How we work
Scope first, named engineers, biweekly demos, and you keep the repo.
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Scope before code
We write what is being built, what is excluded, integrations, dates and cost basis before the build starts. Changes get quoted before they get coded.
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Talk to the people doing the work
You meet named engineers and designers. There is no account manager translating technical questions in both directions.
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Working software every two weeks
Increments land on staging you can open and use. Progress you can click on beats progress in a status report.
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You own everything
Repository, cloud account, domains and credentials stay yours. We work in your accounts wherever possible.
FAQ
Answers specific to api development — stacks, engagement and what we actually ship.
Can you integrate with our ERP/EHR?
If it has an API or a documented exchange format, yes. We will say early if vendor access is the blocker.
Do you provide API docs?
Yes — OpenAPI or equivalent, written for the people who will call it.
REST or GraphQL?
We choose based on clients and change patterns. Many products use REST; GraphQL fits when consumers need flexible queries.
How do you handle vendor failures?
Retries, idempotency, observability and clear failure modes — integrations that break silently are not acceptable.
Can you build partner-facing APIs?
Yes — versioned public or partner APIs with auth, rate limits and documentation for the teams that will integrate.
Related
Services that often sit beside api development on the same roadmap.
Why Three Index
AI-first software development company in Ahmedabad. Founded 2020. Fifty-plus IT professionals. Five hundred-plus projects shipped.
We are a software engineering company: large enough to staff serious products and small enough that the people who wrote a module can still explain it. See how we operate, our AI development work, browse case studies, read the FAQ, or join the team.
Tell us what you are trying to build.
Send a short description of the project. You will get a reply from someone technical — with questions worth answering, not a brochure.