API Development Services

The work falls into three jobs. You may need only one of them.

• Exposing your own system. A clean interface in front of a database or legacy application so web, mobile and partner software can use it.
• Creating a product API. A public or partner-facing interface with keys, usage limits, documentation and a developer portal.
• Connecting other people’s systems. Gateways and adapters that sit between your software and outside services. For that last job, see third-party API integration.

Typical signals that you need api development services: two apps duplicate the same business logic, a partner asks for a data feed you currently email as a file, or every new screen needs a custom back-end change.

No style is best everywhere. The right choice depends on who calls the API and how.

Many products use more than one. A common pattern is REST for partners, GraphQL for your own front ends, and webhooks to push changes. Teams that search for REST API development or GraphQL API development are usually asking the same question: who are the callers?

In a design-first process the contract is written before the code. Teams agree on resources, field names, error formats and authentication in a machine-readable description, for example an OpenAPI file. Front-end and partner developers can then build against a mock server while the real one is under construction.

The contract becomes the source for reference documentation, test cases and client libraries, so the docs cannot drift from the behavior.

Versioning is how you change something people already use. These habits keep clients working:

• Add fields and endpoints freely, but never remove or rename them within a version.
• Publish a deprecation notice with a clear date before retiring anything.
• Return consistent, documented error codes so clients can react in code.
• Make write operations safe to repeat, so a retry after a timeout does not charge a customer twice.
• Set rate limits and tell callers how they work.

APIs expose business logic directly, so attackers probe them systematically. The most frequent flaw is broken authorization: a caller changes an identifier in the request and receives somebody else’s record. Authentication proves who is calling, while authorization decides what that caller may touch, and both need checking on every request.

Use the OWASP Top 10 (opens in a new tab) as a baseline and the OWASP Application Security Verification Standard (opens in a new tab) as a detailed checklist for what to test. Practical controls include:

• Standard token-based authentication, with short-lived access tokens and scoped permissions.
• Object-level and function-level authorization checks in code, not only at the gateway.
• Input validation and strict response schemas, so internal fields are never exposed by accident.
• Rate limiting, request size limits and logging that records who called what.
• Secrets kept in a vault, never in code or client apps.
• An inventory of every endpoint, including old versions, so nothing stays exposed by neglect.

The CISA Secure by Design (opens in a new tab) principles push the same idea: make the safe configuration the default so customers do not have to opt in.

Two real developments matter. First, AI assistants and agents now call business systems through APIs, so a clearly described, narrowly scoped API is what lets an assistant look up an order without being able to refund every order. Treat such callers like any other client: least privilege, logging, and rate limits.

Second, many products wrap a hosted AI model behind their own API. Doing so lets you control prompts, filter sensitive data, record usage and swap providers later. The NIST AI Risk Management Framework (opens in a new tab) is a useful reference for the governance questions this raises.

• Banking and fintech: an account-data API that lets a customer share transactions with a budgeting app, with consent recorded for each request.
• Retail: one stock-and-pricing API consumed by the website, store tablets and marketplace connectors, so the numbers always agree.
• Healthcare: a scheduling interface that lets approved partner apps book appointments without direct database access.
• Logistics: tracking webhooks that tell customers’ systems when a shipment changes status.

These are illustrative scenarios, not Kramate client results.

APIs move personal data, so privacy law follows them. Confirm specifics with legal counsel.

• USA: requirements depend on sector and state. Health data brings HIPAA, and the California Consumer Privacy Act (opens in a new tab) gives residents rights over what you collect and share.
• UK: the UK GDPR and Data Protection Act 2018 apply, as explained in the ICO guidance (opens in a new tab). Banking has its own open banking standards for regulated data sharing.
• Australia: the Australian Privacy Principles (opens in a new tab) cover personal information. The Consumer Data Right sets rules for sharing data through accredited channels in some sectors.
• Singapore: the Personal Data Protection Act applies, and the PDPC (opens in a new tab) publishes guidance. Financial services regulators encourage standardized APIs.

Ask where API traffic and logs are stored, because logs often contain personal data. Agree support hours for outages before launch.

Endpoint count is a poor guide to price. What moves the estimate is:

• How much business logic sits behind each call, and how clean the underlying systems are.
• Authentication model, roles and consent handling.
• Number and age of the systems being connected.
• Documentation quality, developer portal, sandbox and client libraries.
• Performance targets, rate limiting and monitoring.
• Versioning commitments to outside developers, which create a long maintenance tail.

Fixed price works when the contract is agreed up front. A dedicated team suits a product API that will grow, and hourly work suits fixes and extensions. Whatever model you choose for api development services, budget for monitoring and a support period after launch, since real callers always find cases that testing missed.

1. Ask to see a sample contract and documentation from a past or comparable project.
2. Ask how authorization is tested, not only authentication.
3. Check the versioning and deprecation policy they would apply to you.
4. Look for automated contract tests that run on every change.
5. Confirm ownership of code, specifications and documentation.
6. Request a recent independent assurance report such as SOC 2 (opens in a new tab) if your customers will demand one, and read what it covers.

You get a named project manager, updates in Slack or Teams each day, and a review of working software at the close of every two-week round. We sign an NDA before detailed talks and hand over all intellectual property, including the API specification. Day to day we follow Kramate’s delivery approach. These api development services connect naturally with microservices development and enterprise application integration.

Our engineers use least-privilege access, encrypted devices, peer review and regular security testing, and can lead the build or join your team. Fixed-price, dedicated-team and hourly options are available after a free consultation and an estimate within 24 hours.

• OWASP Top 10 (opens in a new tab)OWASP
• OWASP Application Security Verification Standard (opens in a new tab)OWASP
• Secure by Design (opens in a new tab)CISA
• AI Risk Management Framework (opens in a new tab)NIST
• California Consumer Privacy Act (CCPA) (opens in a new tab)California Attorney General
• UK GDPR guidance and resources (opens in a new tab)UK ICO
• Australian Privacy Principles (opens in a new tab)OAIC
• Personal Data Protection Commission Singapore (opens in a new tab)PDPC
• SOC 2 - Trust Services Criteria (opens in a new tab)AICPA