API development and integration services
API development and system integration services: REST and GraphQL APIs for your products and partners, and integrations that connect your CRM, ERP, payment providers and SaaS tools, with retries, monitoring and alerts on every connection.
API and integration work we take on
Contract-first REST APIs
An OpenAPI document agreed before the code, validation at the edge, errors returned as Problem Details, and versioning rules written down before the first client depends on them.
GraphQL and gRPC
GraphQL for front ends that need flexible queries over many entities, gRPC for fast service-to-service calls, each with its schema in source control and breaking changes caught in the pipeline.
Third-party integrations
Payment providers, Salesforce and HubSpot, accounting systems, Microsoft Graph and marketplaces, written as adapters so the vendor’s SDK stops at the edge of your code.
Event-driven messaging
Queues and event streams on Azure Service Bus, Kafka or RabbitMQ, with idempotent consumers and dead-letter queues, so a failed message is visible and can be replayed.
Webhooks in both directions
Signed outgoing webhooks with retries for your customers, and incoming ones verified, de-duplicated and processed off the request path.
API security and gateways
OAuth 2.0 and OpenID Connect with scoped tokens, rate limits and a gateway such as Azure API Management, with every input validated at the boundary.
Hire API developers
Dedicated API developers
API developers who join your team full time, work in your tools and process, and report to your lead. You interview them; we carry the Ukrainian contract, payroll, invoicing and leave.
API development projects
A defined piece of API development with a scope, a fixed plan and a named lead on our side who owns the result and reports progress in your channels.
Ongoing API development
API development as a continuing service: the same people every month, a backlog you prioritise, and hours you can see in our portal and on the invoice.
The dedicated team page explains how specialists join your team, and the outsourcing page covers project delivery, take-overs and how we charge.
Who works on your API development
Backend engineers
.NET, Python, Java, Node.js or Go services and APIs
Integration engineers
Adapters, queues and data mapping between systems
Cloud engineers
Gateways, networking, secrets and monitoring
QA engineers
Contract tests and API test automation
How we build APIs and integrations
Every API starts as a contract: an OpenAPI or GraphQL schema reviewed with the people who will call it, implemented with validation at the boundary, and clients generated from the same document so the two sides cannot drift apart.
Every integration assumes the other side will fail. Calls have timeouts and retries with backoff, messages that cannot be processed go to a dead-letter queue with an alert, and credentials live in a vault rather than a configuration file. The integrations our own platform runs on, with Microsoft Graph, Teams, Telegram and external time trackers, are built the same way.
Other solutions we deliver
MVP development
MVP development services for founders and product teams: scoping, a Figma prototype, a web or mobile build and launch on a stack that carries the next version, by dedicated MVP developers or as a project.
SaaS development
SaaS development services: multi-tenant architecture, subscriptions and billing, enterprise single sign-on, support tooling and releases without downtime, by dedicated SaaS developers or as a project.
Web application development
Web application development services: customer portals, internal tools, dashboards and progressive web apps, with the backend and hosting included, by dedicated web developers or as a project.
Legacy modernisation
Legacy software modernisation services: take-overs that start with a read-only review, upgrades to current .NET, Java and PHP, and replacement in steps, by dedicated engineers or as a modernisation project.
Cloud migration
Cloud migration services: workload assessment, landing zones in Terraform, and database and application moves to Azure, AWS or Google Cloud with a planned cut-over, by dedicated cloud engineers or as a project.
Questions about API development and integrations
REST or GraphQL?
REST for most public and partner APIs, because every client and tool understands it and it caches well. GraphQL when several front ends need different shapes of the same data and the round trips add up. We recommend one per API, and some systems sensibly use both.
Can you integrate a system that has no API?
Usually, yes: through its database, file exports or an SFTP drop, wrapped in a service that gives the rest of your systems a proper API and raises an alert when the source changes shape.
Can you document and test the API we already have?
Yes: an OpenAPI document produced from the running API, contract tests that pin its current behaviour, and a list of the inconsistencies worth fixing before more clients depend on them.
How quickly can API developers start?
When the right API developer is available, the start is gated only by your interview and the NDA and IP assignment. Otherwise we run a search, which typically produces candidate profiles within two to three weeks, and nobody starts until you have said yes.
How do we hire API developers through BigTree108?
Tell us the work, the seniority and the hours you need. We propose one or two people with their profiles, you interview them the way you would interview your own hire, and you sign one agreement with BIG TREE 108 LLC and receive one invoice a month.
Who owns the work they produce?
You do. Every specialist has a signed contract with BigTree108 that assigns all work product to the company, and our agreement with you assigns it onward. Code, designs and documents are delivered into your own repositories and tools, not kept where only we can change them.
Need an API built or systems connected?
Tell us the systems involved and what has to flow between them. You get an answer within one business day: an integration plan, an estimate or candidate profiles.