(00) / API development

API development.
Communication, engineered.

REST and event-driven APIs built with Node.js and Fastify. Secure, documented, observable.

(01) / The request

Every request,
understood.

Schema-first. Contracts before implementation. OpenAPI and TypeScript types any team can build against.

(02) / The guard

Hardened
at the door.

Authentication, validation, rate limits. Every packet checked before it touches your data.

(03) / The route

Routed where
it belongs.

Postgres, cache, event streams. Clean contracts between services, tested with real failure scenarios.

(04) / The response

Answered.
Fast and observable.

Logs, metrics and alerts wired in from day one. You see exactly what happens in production.

Build your APIThe proof
Scroll
(05) / Observable

// every request, logged, traced, observable

tail -f /api/server.log

~/api/server.log — tail -flive

// waiting for traffic...

(06) / Numbers

// what production looks like

GET /metrics

0.0%

Uptime target

0ms

p95 latency

0+

req/s capacity

0%

OpenAPI typed

(07) / What You Get

// the deliverables, line by line

GET /deliverables

{
  • "01":"REST or event-driven services on Node.js or Fastify.",
  • "02":"OpenAPI / TypeScript types you can hand to any frontend team.",
  • "03":"Authentication, validation, rate limits. Hardened from day one.",
  • "04":"Logs, metrics, alerts. You see what's happening in production.",
  • "05":"Migration path for every breaking change. No surprises for clients."
}
(08) / Differently

// the part most teams skip

git diff legacy.. with-me

--- legacy/build+++ with-me/build
@@ -1,4 +1,4 @@
- // generic team approach
+AI explores edge cases before they hit production.
+I write the docs as I write the code. Not as an afterthought.
+Schema-first. Contracts before implementation.
+Tested with real failure scenarios. Network drops, race conditions, replays.
(09) / Guarantee

// every promise is a passing test

npm test sla.spec.ts

PASSsla.spec.ts4 passed, 0 failed
describe('sla guarantees', () => {
✓it('99.9% uptime targets with monitoring proof.')
✓it('Documented response times. SLOs you can hold me to.')
✓it('Source code and infrastructure access. Full ownership.')
✓it('30 days of free fixes after launch.')
});
(10) / Why Me

// the engineer behind the API

$ whoami --verbose

user@pauljulianheise.com4 attributes
identity
→A decade of building backends across PHP, Node.js, Python.
stack
→I've run my own infrastructure. I know what breaks.
model
→One contact. One context. End to end.
contract
→You don't pay for a sales layer. You pay for code that works.
(11) / In Your Team

Also available embedded. Your team, this discipline.

Not every project needs the full chain. If you run your own team, I join it in exactly this discipline. As a freelancer, inside your workflow.

  • 01
    Senior backend engineer in your team. Your repo, your standards.
  • 02
    Node.js, Fastify, TypeScript, Kafka, PostgreSQL. No ramp-up drama.
  • 03
    Owns a service end to end or pairs on yours. Both work.
  • 04
    Part-time or full focus. Weekly availability agreed up front.
(12) / Start

Ready when you are. Let’s talk.

Get in Touch