Hire API Developers
An API is a promise to other software. Once a mobile app, a partner or a customer depends on a field or a status code, changing it has a cost. API development is therefore mostly about decisions made early: naming, error format, authentication, and what happens when the same request arrives twice.
Our API developers work on your systems as part of your team. They use your repository and your tracker and answer to you. PWTECH employs them and provides continuity if circumstances change.
API design and integration jobs
The work falls into two halves: building interfaces that others call, and calling interfaces that others built. Most engagements involve both.
Designing a new API
Resources, URLs, status codes and error bodies are agreed in an OpenAPI document before implementation. Front-end and mobile developers can then work against a mock server while the real one is being written.
Third-party integrations
Payment providers, CRMs, accounting packages, couriers, messaging services. Each call has a timeout and a retry rule, and provider outages are handled so that your application degrades instead of failing outright.
Webhooks, sending and receiving
Incoming webhooks are verified by signature, acknowledged quickly and processed on a queue. Outgoing webhooks are signed, retried with increasing delays, and logged so a customer can be shown exactly what was sent.
Authentication and access
OAuth 2.0 and OpenID Connect flows, API keys with scopes, short-lived tokens with rotation. Authorisation is checked per object as well as per endpoint, since that gap is among the most common API weaknesses.
Exposing a legacy system
A clean HTTP interface placed in front of an old database, a SOAP service or a file-based exchange, so newer applications can use the data without knowing how it is stored.
Versioning and deprecation
Adding fields without breaking clients, introducing a new version when a breaking change is unavoidable, measuring who still calls the old one, and retiring it on a published date.
Protocols, specifications and test tools
APIs are written in many languages. What stays constant is the set of standards and tools around them. Tell us your language and we propose a developer who works in it.
- Styles
- RESTGraphQLgRPCWebhooksWebSocketsSOAP
- Specifications
- OpenAPIJSON SchemaOAuth 2.0OpenID ConnectJWTProblem Details (RFC 9457)
- Server languages
- PHPNode.jsPythonGoC#Java
- Testing
- PostmanBrunoPactk6Schemathesis
- Gateways
- KongAmazon API GatewayAzure API ManagementNginx
- Monitoring
- OpenTelemetryPrometheusGrafanaSentry
Who should design the API and who should build it
Implementation and design are different skills. An endpoint can be coded by a junior; the contract it implements should come from someone who has lived with the consequences of a poor one.
Junior
Implements endpoints from a finished specification, writes request validation and tests, and connects to well-documented third-party services by following their guides.
Choose when: the contract is already written and another developer reviews the implementation.
Mid-level
Builds an integration or a group of endpoints independently, including pagination, filtering, error handling and documentation. Thinks about what happens on timeout and on duplicate delivery without being prompted.
Choose when: you have a list of integrations or endpoints and want them completed reliably.
Senior
Writes the contract. Decides on the API style, authentication model, versioning policy and rate limits, and foresees how the design will cope with clients you do not control. Reviews security against the OWASP API Security list.
Choose when: outside parties will consume the API, money or personal data passes through it, or no standard exists yet.
Agreeing the contract, then the engagement
Tell us what must connect
Name the systems involved, the language of your back end, and any documentation you hold for the third-party services. Existing API specifications are especially useful.
Interview the developer we put forward
One person, identified by name, with experience in your language. You speak with them yourself and can turn them down.
Start with one integration point
A single endpoint or one webhook handler, delivered with tests and documentation, shows the standard you can expect.
Regular delivery and reporting
Work items sit in your tracker. We write to you weekly with what went live and what is awaiting a decision. Invoices are monthly.
API developer hourly and monthly cost
Our rates are published. Pick the role and move the sliders for an indicative budget.
Rate card
| Role | Hourly | Monthly* |
|---|---|---|
| Frontend / WordPress | $30 | $4,800 |
| Backend / API | $32 | $5,120 |
| Full-stack | $35 | $5,600 |
| Mobile (React Native / Flutter) | $35 | $5,600 |
| DevOps / Cloud | $40 | $6,400 |
| AI / Automation engineer | $45 | $7,200 |
| QA / Test engineer | $25 | $4,000 |
| UI / UX design | $28 | $4,480 |
*160 hrs/month full-time. Rates are indicative for planning, in USD (other currencies are converted at an indicative rate), and depend on seniority, contract length and timezone overlap. Longer engagements and multi-role teams are discounted — ask.
Is a dedicated API developer what you need?
We are a good choice when
- Your product relies on several outside services and the connections need constant care.
- You are opening your platform to partners and need a public API done properly.
- Mobile and web teams are waiting on back-end endpoints.
- You are an agency whose projects regularly include integration work.
Look elsewhere when
- A ready-made connector or automation tool already does what you need. Use it; custom code would cost more.
- You need a single small script and no maintenance.
- The third-party system has no API and forbids automated access. We will not work around a provider's terms.
- You want a fixed price before the list of systems and data fields is known.
Questions on versioning, security and ownership
REST, GraphQL or gRPC?
REST for public APIs and most web back ends, because every client and tool understands it. GraphQL when front ends need to shape their own queries across many related objects. gRPC for calls between your own services where speed and strict typing matter.
How do you prevent a payment or order being processed twice?
With an idempotency key. The client sends a unique value with the request, the server stores the outcome against it, and a repeated request returns the stored outcome without acting again. The same principle applies to incoming webhooks.
How should we version our API?
Avoid new versions for as long as possible by only adding, never removing or renaming. When a breaking change is necessary, put the version in the URL or a header, run both side by side, and give consumers a clear retirement date.
Can you document an API that has no documentation?
Yes. We read the routes and handlers, record real requests and responses, and produce an OpenAPI file from them. The file then serves for generated reference pages, client code and contract tests.
Who owns the code and the specification?
You own both. They are committed to your repository, and ownership and confidentiality are defined in the agreement at the start.
Who holds the credentials for third-party services?
You do. Accounts with providers are opened in your company name, and keys are kept in your secret store. The developer is given access for as long as the engagement lasts and you can revoke it at any time.
List the systems that need to talk to each other
Name the applications or services involved, the language your back end is written in, and what data should move between them. We will reply within one business day.