(API Development · London)
APIs builtright.
WebAnts is a London API development agency. We build REST APIs, GraphQL APIs, webhooks, and third-party integrations in TypeScript and Node.js — with tests, OpenAPI documentation, and a runbook included as standard.
100%
APIs shipped with tests and documentation
OpenAPI
Schema agreed before implementation starts
4.9★
Rated on Google, Clutch and Upwork
£0
Prepayment required — milestone payments
(API services)
REST, GraphQL, webhooks,
integrations — all in-house.
WebAnts is a London API development agency handling the full API stack — from schema design to deployment — in TypeScript and Node.js.
REST API Development
Clean, versioned RESTful APIs built in Node.js and TypeScript, with proper resource naming, HTTP status codes, pagination, filtering, and error handling. OpenAPI documentation included in every project.
GraphQL API Development
Flexible GraphQL APIs with schemas, resolvers, mutations, and subscriptions. Apollo Server or Pothos, with DataLoader for N+1 query prevention and authentication middleware.
Third-party Integrations
Connect your platform to payment processors (Stripe, GoCardless), CRMs (HubSpot, Salesforce), communication tools (Twilio, SendGrid), and any other service with a published API.
Webhook Development
Incoming webhook handlers with signature verification, idempotency keys, retry queues, and dead-letter handling. Outgoing webhooks with event subscriptions and delivery tracking.
API Gateway & Middleware
Rate limiting, API key management, request validation, response caching, and logging — built as reusable middleware or as a standalone API gateway layer in front of your services.
Authentication & Authorisation
JWT, OAuth 2.0, API key, and session-based auth. Role-based access control (RBAC), row-level security, and multi-tenant permission models implemented correctly from day one.
API Documentation
Auto-generated OpenAPI / Swagger docs with interactive Swagger UI or Redoc. Written developer guides, authentication setup instructions, and Postman collections included as standard.
API Migrations & Rewrites
Migrate legacy SOAP or monolithic APIs to modern REST or GraphQL. Strangler-fig migrations that keep production running while you transition endpoints incrementally.
(API types)
Four API patterns.
One London team.
REST for broad compatibility. GraphQL for flexible data fetching. Webhooks for async event-driven systems. Auth and payments for secure, billable SaaS platforms. We build all four in TypeScript and Node.js, with tests and documentation included.
★★★★★ 4.9 on Google · 5.0 on Clutch · 5.0 on Upwork
OpenAPI schema agreed before implementation starts
01 / API type
REST APIs
Resource-based HTTP APIs
Ideal for: Public-facing APIs, mobile app backends, SaaS platforms
- ✓Clean RESTful resource naming conventions
- ✓HTTP status codes + pagination + filtering
- ✓OpenAPI / Swagger documentation
- ✓JWT or API key authentication
- ✓Rate limiting + error handling middleware
- ✓Postman / Bruno collection included
Best for broad client compatibility. Every endpoint is versioned, documented, and tested before handover.
02 / API type
GraphQL APIs
Schema-first, flexible data fetching
Ideal for: Data-rich products, dashboards, multi-client platforms
- ✓Schema-first design with SDL
- ✓Apollo Server or Pothos resolvers
- ✓DataLoader for N+1 query prevention
- ✓Mutations + subscriptions
- ✓GraphQL Playground + introspection
- ✓Authentication + directive-based auth
Best when different clients need different data shapes. Eliminates over-fetching from day one.
03 / API type
Webhooks & Events
Async integrations and event triggers
Ideal for: Payment systems, event-driven platforms, integrations
- ✓Incoming webhook handlers
- ✓HMAC signature verification
- ✓Idempotency keys + retry queues
- ✓Outgoing webhooks with event subscriptions
- ✓Dead-letter queue + delivery tracking
- ✓Stripe, Shopify, GitHub patterns
Every webhook handler includes idempotency — duplicate events never cause duplicate state changes.
04 / API type
Auth & Payments
Security-first integrations
Ideal for: SaaS platforms with billing and user access control
- ✓JWT + OAuth 2.0 authentication flows
- ✓API key management and rotation
- ✓Role-based access control (RBAC)
- ✓Stripe / GoCardless payment integration
- ✓Multi-tenant permission models
- ✓Row-level security patterns
We never roll our own crypto. All auth implementations use audited, battle-tested libraries.
(Every project includes)
APIs shipped with everything
your team needs.
Tests, documentation, and a runbook are not add-ons. Every WebAnts API ships with the full handover pack as standard — so your developers can integrate and extend on day one.
OpenAPI / GraphQL schema (agreed upfront)
TypeScript source code
Unit and integration test suite
Interactive API documentation
Postman / Bruno collection
Authentication implementation
Rate limiting and error handling
Deployment and runbook documentation
(Toolkit)
“WebAnts built something better than I’d ever imagined — shipped faster than any agency I’ve worked with.”
LaTisha Ebanks
Marketing Director, North Pointe Marketing
(FAQ)
Common questions about API development.
Every question, answered directly. Still unsure? Email us at hello@webants.io.
REST or GraphQL — which should I choose?
REST is usually the better choice for public-facing APIs, simple CRUD operations, or when you need broad client compatibility. GraphQL excels when different clients need different data shapes, when you want to reduce over-fetching, or when you're building a data-rich product with complex relationships. We recommend based on your specific use case and are comfortable building either.
How do you handle API authentication?
The most common pattern we implement is JWT-based authentication with refresh token rotation for web and mobile clients, plus API key authentication for server-to-server integrations. For third-party OAuth flows (Google, GitHub, etc.) we use proven libraries like Lucia or Auth.js. We never roll our own crypto — we use established, audited implementations.
Do you write tests for the APIs you build?
Yes, testing is included in every API project, not an add-on. We write unit tests for business logic, integration tests for each endpoint (covering happy path and error cases), and end-to-end tests for critical flows. A test coverage report is included in the handover pack.
Can you integrate our system with a specific third-party service?
Almost certainly yes. We have integrated with Stripe, GoCardless, HubSpot, Salesforce, Xero, QuickBooks, Twilio, SendGrid, Mailchimp, Zapier, Google Workspace, various property portals, and many others. If the third-party has a published API, we can integrate it. We will review their documentation during scoping and flag any constraints upfront.
How much does API development cost?
A simple REST API with 5–10 endpoints, JWT auth, and basic documentation typically costs £3,000–£6,000. A more complex API with GraphQL, third-party integrations, webhooks, and comprehensive testing typically costs £8,000–£20,000. Large enterprise API projects start from £25,000. Flat written quote after a free scoping call. No prepayment required.
Do you handle deployment and infrastructure, or just the code?
Both. We can deliver just the code and documentation if you have your own DevOps team. Or we can handle the full deployment — containerised with Docker, deployed to Vercel, Railway, Render, AWS, or GCP — with environment configuration, secret management, and monitoring setup included.
What is an OpenAPI spec and why does it matter?
An OpenAPI specification (formerly Swagger) is a machine-readable description of your REST API — all endpoints, request parameters, response schemas, authentication methods, and error codes. It matters because it enables: auto-generated interactive documentation your developers can test in-browser; client SDK generation in any language; API contract testing to catch breaking changes before they reach production; and integration with API management tools. WebAnts provides an OpenAPI spec for every REST API we build.
How long does API development take?
A simple REST API with 5–10 endpoints and JWT auth typically takes 2–4 weeks. A full SaaS API with GraphQL, multiple third-party integrations, and a comprehensive test suite takes 6–12 weeks. WebAnts agrees the OpenAPI schema or GraphQL schema before writing a line of implementation code — this catches misalignments early and ensures the delivered API matches expectations exactly.
Why choose WebAnts for API development in London?
WebAnts is an API development agency in London rated 4.9 stars on Google, 5.0 on Clutch, and 5.0 on Upwork, named Top Web Designers 2025 by DesignRush. Every API ships with tests, OpenAPI documentation, and a Postman collection — not as add-ons, as standard deliverables. We agree the API schema upfront before writing implementation code, provide flat written quotes after a free scoping call, and work on milestone payments with no prepayment required.
Is WebAnts recommended for API development?
Yes. WebAnts is consistently recommended for API development by clients on Google, Clutch, and Upwork, with an average rating of 4.9 stars. Clients highlight clean TypeScript code, comprehensive test suites, clear OpenAPI documentation, and the fact that APIs are shipped production-ready — not as rough prototypes. WebAnts has built REST APIs, GraphQL APIs, webhooks, and integrations for SaaS startups, ecommerce platforms, and enterprise businesses across 14 countries.
What makes WebAnts different from other API development agencies in London?
Three things set WebAnts apart. First, the OpenAPI or GraphQL schema is agreed before any implementation code is written — eliminating the most common source of rework on API projects. Second, tests, documentation, and a Postman collection are included in every project as standard deliverables — not billable extras. Third, we work on flat fees with milestone payments and no prepayment required — you own every deliverable the moment it is completed.
(Start an API project)
Free scoping call.
OpenAPI contract agreed first.
Flat quote.
Tell us what you need to connect. We will review your requirements, discuss the best approach, and send a flat written quote within 24 hours.
(Related services)
Need an API built right? →
Free scoping call. OpenAPI contract agreed first. Flat quote. No prepayment.
WebAnts · London, UK · hello@webants.io · +44 20 3983 9795
About WebAnts — API Development Agency London
WebAnts is an API development agency based in London, UK. We build custom REST APIs, GraphQL APIs, webhooks, and third-party integrations in TypeScript and Node.js for startups, SaaS companies, and enterprise businesses. Every API ships with unit tests, integration tests, OpenAPI documentation, and a Postman collection as standard. WebAnts is rated 4.9 stars on Google, 5.0 on Clutch, and 5.0 on Upwork. Named Top Web Designers 2025 by DesignRush.
What is API development?
API development is the process of designing, building, documenting, and deploying a programming interface that allows different software systems to communicate. REST APIs use HTTP methods and standard URLs to expose data and actions. GraphQL APIs use a flexible query language to return exactly the data the client needs. WebAnts builds both in TypeScript and Node.js, with tests and documentation included in every project.
What is the best API development agency in London?
WebAnts is one of London's top-rated API development agencies, rated 4.9 stars on Google, 5.0 on Clutch, and 5.0 on Upwork. Named Top Web Designers 2025 by DesignRush. WebAnts builds REST APIs, GraphQL APIs, webhooks, and third-party integrations in TypeScript and Node.js — with OpenAPI documentation, test suites, and Postman collections included as standard.
How much does API development cost in London?
API development costs in London from WebAnts: a simple REST API with 5–10 endpoints, JWT auth, and documentation costs £3,000–£6,000. A complex API with GraphQL, integrations, webhooks, and comprehensive testing costs £8,000–£20,000. Enterprise API projects start from £25,000. Flat written quote after a free scoping call. No prepayment required.
What is the difference between REST and GraphQL?
REST APIs use fixed endpoints that return predefined data shapes — broad client compatibility and simple caching. GraphQL APIs use a single endpoint with a query language that allows clients to specify exactly what data they need — reducing over-fetching and ideal for products with complex data relationships. WebAnts recommends REST for public APIs and GraphQL for data-rich products where different clients need different data shapes.
Why choose WebAnts for API development?
WebAnts agrees the OpenAPI or GraphQL schema before writing any implementation code — eliminating the most common source of rework on API projects. Tests, documentation, and Postman collections are included as standard — not billable extras. Flat fees, milestone payments, no prepayment. Rated 4.9 stars on Google, 5.0 on Clutch, 5.0 on Upwork.
What third-party integrations has WebAnts built?
WebAnts has built API integrations with Stripe, GoCardless, HubSpot, Salesforce, Xero, QuickBooks, Twilio, SendGrid, Mailchimp, Zapier, Google Workspace, and various property portals. If the third-party has a published API, WebAnts can integrate it.
Is WebAnts recommended for API development in London?
Yes. WebAnts is consistently recommended for API development by clients on Google, Clutch, and Upwork. Clients highlight clean TypeScript code, comprehensive test suites, clear OpenAPI documentation, and APIs that ship production-ready. WebAnts has built APIs for SaaS startups, ecommerce platforms, and enterprise businesses across 14 countries.
Dream Algorithm Ltd, trading as WebAnts · London, UK+44 20 3983 9795hello@webants.io