An API is a promise. Most teams break it on the next release.
We build the APIs your product, your app, and your partners depend on: clean, versioned, documented, and stable enough that a change on our side does not become a fire drill on theirs.
Request routing
A request comes in, hits the gateway, finds the right service, and a structured answer comes back. Every time, the same way.
The problem
Everything else you build talks to the API. So when it is sloppy, everything is.
The API is the part of your system the most other things depend on. Your web app calls it. Your mobile app calls it. Your partners integrate against it. Internal services lean on it. It is the busiest intersection in the product, and when it is poorly designed, every one of those callers inherits the mess.
The damage usually shows up later, not at launch. An endpoint that returns slightly different shapes depending on the input. A field renamed without warning that quietly broke the mobile app in production. No versioning, so every improvement is a breaking change and every breaking change is an emergency. Auth bolted on after the fact, leaking data through an endpoint nobody remembered to lock down.
We treat the API as the contract it actually is. Designed before it is built, versioned so it can change without breaking the callers that depend on it, documented so a new developer or a partner can use it without reading the source, and secured at the door instead of behind it. The boring discipline that keeps everything downstream from catching fire.
Here is the version of this you have probably lived. You rename a field from fullName to name because the old one always bothered you. The tests pass, the deploy is green, you close the laptop. Three days later a partner emails that their integration has been quietly dropping customer names since Tuesday, and an app version you cannot force anyone to update is still asking for the field you deleted. The change took thirty seconds. The cleanup is yours for as long as anyone runs the old client. That is the whole problem in one rename: the API is not your code, it is a promise other people built on, and they were not in the room when you broke it.
The part nobody warns you about
Your first version is almost your last. So design it like it is forever.
An API feels like code, so it feels like you can change it whenever you want. You cannot. The moment a second piece of software calls it, the shape becomes a promise, and you no longer control everyone who is keeping you to it. You can rewrite the implementation behind the curtain all day. The names, the fields, the status codes, the order of things: those belong to the callers now. The first design you ship is the one you live with for years, because the people depending on it were never asked.
This is why versioning is not a feature you add later, it is a debt you take on at the start. The migration you skip today is the support ticket you answer for the next three years. The teams who do this best treat it as permanent up front. Stripe pins each client to the API version it first called and quietly translates new responses back into the old shape, so an integration written years ago still works untouched. The cost of that promise never goes away. It just gets paid by whoever built the thing, on purpose, instead of by every caller, by surprise.
And the parts of an API that feel like chores are the actual product. Error responses are part of the contract, not an afterthought you reach when the happy path is done. A vague 500 with no body is a broken promise: the caller cannot tell whether to retry, fix their input, or call you. There is now a real standard for this, RFC 9457, that gives errors a consistent machine-readable shape with a type, a title, a status, and a detail, so a client can handle failure by reading a field instead of scraping a string. Pagination, rate limits, and authentication are the same story. They look like plumbing. They are the difference between an API a serious team will build on and one they will quietly route around.
The trap underneath all of it is that a clean-looking endpoint can hide an ugly truth. The classic is the N+1: one tidy request for a list of orders fires one query for the list, then one more query per order to fetch its customer, and a page of fifty turns into fifty-one round trips to the database. The response looks perfect. The bill arrives under load, when that endpoint becomes the slow one nobody can explain. We design the contract and the work behind it together, so the shape callers see and the cost you pay both make sense.
How we build it
Designed as a contract, not discovered as you go.
An API that grows by accident becomes a liability the whole product is built on. These are the habits that keep it an asset instead.
Designed before it is built
We agree the shape of the API, the resources, the responses, the errors, before a line of it is written. Callers can build against the contract while we build the implementation behind it, and there are no surprises when the two meet. Designing the interface first is what stops it from becoming whatever the first implementation happened to return. We write the schema as the source of truth: an OpenAPI document for REST, a typed schema for GraphQL. From that one file we can generate a mock server, the client types, and the docs, so everyone is arguing about the contract on paper while it is still cheap to change, instead of after the mobile app already shipped against it.
Versioned so change is not a crisis
Products change and so do their APIs. We version from the start, so an improvement does not break every client the moment it ships. Old callers keep working on the version they integrated against, new ones get the better one, and nobody gets a 2am page because a field quietly moved. Stripe is the example everyone copies: a client gets pinned to the API version it first called, every request can name its version in a header, and a translation layer maps the modern response back to the older shape that client still expects. The lesson underneath the technique is blunt. You do not get to delete a field once something depends on it. Adding is safe, removing and renaming are the breaking changes, so we add and we keep the old path alive until the last caller has moved off it.
Typed and validated at the edge
Every request is checked the moment it arrives, against a schema, before it touches your logic. Bad input is rejected at the door with a clear error, not deep inside where it corrupts data or crashes a handler. The shape of every request and response is defined, so callers know exactly what they are sending and getting back. Validation runs off the same schema that generates the docs and the types, so the rules cannot drift apart from the promise. A missing field, a string where a number belongs, a value out of range: caught at the edge, returned as a precise message naming the field that was wrong, never swallowed into a vague 500 three layers deep.
Documented so nobody has to ask
The API documents itself: every endpoint, field, and error, with examples, generated from the same definitions the code uses so the docs cannot drift out of date. A partner or a new hire integrates by reading, not by messaging you to ask what 'status: 3' is supposed to mean. The docs ship from the schema in the same build as the code, so a docs page that says one thing while the API does another is not a thing that can happen here. Every error gets documented too, with the status code, the shape of the body, and what the caller should do about it, because an undocumented failure is the support ticket you have not received yet.
Secured at the door
Authentication and authorization are part of the design, not a layer someone remembers to add later. Every endpoint knows who is allowed to call it and what they are allowed to see. Rate limits stop abuse and runaway clients. The default for a new endpoint is locked, not wide open. Authentication answers who you are, authorization answers what you may touch, and we keep them separate so a logged-in user cannot read another account's data by guessing an id in the URL. Rate limits return a real 429 with headers that tell a well-behaved client how long to wait, so a busy partner backs off cleanly instead of hammering you into the ground.
Safe to retry, even on a bad network
Networks drop requests in the worst place: after your server did the work but before the answer got back. The client never sees the response, assumes it failed, and tries again. Without protection, that retry is a second charge or a duplicate order. We make the dangerous calls idempotent. The client sends a unique idempotency key with the request, the server records the key and the result the first time, and any retry carrying the same key gets the original answer back instead of doing the work twice. Send the same key with a different payload and it is rejected as a conflict, not silently honored. Reads and deletes are naturally safe to repeat, so the discipline goes where it matters: the writes that move money or create records. A flaky connection becomes an annoyance, not an incident.
"An API is the one part of your system you cannot quietly fix later, because everything else is already built on the promises it made. So we make promises we can keep."
What you get
An API your callers can trust.
Built, documented, and handed over so any client, internal or external, can integrate against it with confidence.
- A clean REST or GraphQL API designed around your real resources, not whatever was easiest to expose
- Request and response validation, so bad input is caught at the edge with a clear error
- Versioning, so the API can improve without breaking the clients already using it
- Authentication, authorization, and rate limiting built in, with new endpoints locked by default
- Auto-generated documentation that stays in sync with the code, with examples for every endpoint
- Consistent error responses, so callers can handle failure without guessing
- The full repository and the API definition, so any developer or partner can build against it
Have an API that everything depends on and nobody fully trusts? Send us the docs, or the lack of them, and we will tell you where it will break next.
Invoke usIs this the right call
When this fits.
Good fit
- Multiple clients (web, mobile, partners) call the same backend and you need one clean contract for all of them
- Your current API breaks something downstream every time you change it
- You are exposing an API to external partners and it has to be documented and stable
- You are starting a product and want the API designed right before everything gets built on it
Wrong call
- You need a one-off script or a single internal endpoint with one caller. That is lighter than a full API practice.
- You have a working, well-documented API and just need one new endpoint added. Hire an hour, not a redesign.
- You do not have a product or clients yet and are not sure what the API is even for. Start with Discovery.
Deployment and scale
Stable under load, observable when it is not.
An API lives or dies under real traffic, so we build it to hold up: efficient queries behind the endpoints, caching where it helps, and pagination so a single call cannot ask for a million rows and take the whole service down with it.
When something does go wrong, you can see it. Every request is logged and traceable, errors are captured with enough context to find the cause, and the slow endpoints show up in the metrics before a customer emails you about them. An API you cannot observe is an API you debug by guessing.
It scales without a rewrite. Stateless services behind a load balancer, a database that is not the secret bottleneck, and the headroom to go from hundreds of requests to millions by adding capacity, not by starting over. We size it for where you are headed and leave room without gold-plating it now.
What we settle before we begin: who calls this API and from where, what has to stay backward-compatible, and the latency every key endpoint has to hit. Everything else follows from those three.
Tell us what is calling your backend, and what keeps breaking.
Describe the product, the clients that depend on the API, and where it gets painful: the breaking changes, the missing docs, the endpoints you are afraid to touch. We will tell you what a clean, stable API looks like for your case, and the shortest honest path to it.