API & Platform Integrations

Integration debt is the tax you pay on every feature you ship.

Partner APIs don’t wait. Compliance deadlines don’t move. Neither do we.

Start with a scoping session

See how we work

Spec written in 1–3 sessions · kick-off within 1 week of sign-off

70corridors

Payment integrationsCross-border fintech · 12 countries · 3 years

APIs migratedCompliance fintech · 50% perf uplift

4SoWs

Delivered in 6 monthsCompliance platform · parallel streams

02 / Why it keeps slipping

Three reasons API work stays in the backlog.

Your team means to get to it. Product always wins.

The work is defined. The docs exist. But client requests and features consistently take the sprint. Integration work is important — never urgent. Until a deadline forces the conversation.

API documentation lies.

Especially with enterprise and government systems. Specs are rarely kept current. The real behaviour only surfaces in sandbox — and what passes in sandbox often breaks in production.

Every quarter it slips,
the cost compounds.

Deferred integrations grow coupling, accumulate workarounds, and block downstream work. The manageable backlog in Q1 becomes a re-architecture project by Q4.

03 / How we work

We cut integration time - here’s exactly how.

Built by engineers. Delivered by engineers.

We train a dedicated AI agent on your API spec and the target platform’s documentation. The agent writes the integration code and generates the test suite.

In 9 out of 10 cases, sandbox testing reveals gaps between official documentation and how the API actually behaves. Our engineer identifies them, contacts the vendor directly, and resolves them. The agent handles the predictable work. The engineer handles the judgment calls.

We stay through go-live — including nights and weekends when it matters.

9/10Projects reveal doc-to-reality gaps

on-callWe stay through go-live

04 / What we deliver

From first API call to production - owned end to end.

We take the integration from spec to go-live. Not consulting, not ticket-filling.

We design, build, test, and hand over with documentation your team can own without us.

Third-party API integration

banking rails, payment gateways, partner systems, AML platforms

API emulation layers

backward-compatible wrappers enabling cloud-to-cloud migrations with zero client-side changes

Performance optimisation

sync vs async architecture, caching, circuit breakers

Legacy API migration

moving from deprecated endpoints without downtime

Identity translation

identifier mapping between systems to remove integration friction blocking adoption

Compliance-grade integrations

audit trails, error logging, regulatory alignment

Webhook architecture

event-driven integration with consumer chains, classification logic, retry logic

Auth & security

OAuth2, API key management, token rotation, gRPC

Observability setup

structured logging, metrics, and alerting from day one

05 / Proof

What we’ve shipped

Cross-border paymentsFintech · UKUK · 3-year engagement

Banking partner integrations across 12 countries. Built and maintained APIs enabling international money transfers at scale in a regulated environment.

70 Corridors

12 Countries

3 year engagement

Compliance platformUK4 SoWs6 months

Four parallel engineering streams delivered over six months:

Four parallel engineering streams: webhook infrastructure, identity translation, backward-compatible API emulation, and gRPC performance optimisation for search creation. Google PSF-funded across the engagement.

4 SoWs delivered

80%+ test coverage

Google PSF-funded

Performance uplift before and after rewrite

Fintech3 months

30 API migrations with 50% performance uplift. Full codebase rewrite with RLS optimisations: 47% average latency reduction, 75% p90 improvement, 0% error rate.

30 APIs migrated

50% perf uplift

47% latency reduction

06 / Pricing

Fixed scope.
Fixed price.
No surprises.

Final price confirmed after 1–3 scoping sessions.

We write the spec — no homework on your side.

Focused Delivery

from€35,000

4–6 weeks

For teams with one well-defined task. Scope is clear. Timeline is predictable.

What’s included

Discovery + written spec
Dedicated senior engineer
Weekly demos
Handover + documentation

Most common

Platform Delivery

from€65,000

8–12 weeks

For teams where the work touches multiple systems or requires architectural decisions.

Everything in Focused Delivery, plus

Architecture review
Multiple workstreams
Async daily updates
30-day post-delivery support

Custom Engagement

from€120,000

Scope confirmed in discovery

For long-term partnerships, complex migrations, or multi-stream delivery programmes.

Everything in Platform Delivery, plus

Dedicated team (2–4 engineers)
Monthly retainer option
Joint sign-off at each milestone

Not sure which fits?

The scoping session will tell you

07 / Process

Discovery to go-live -
without the handoff gap.

Five phases.

We are a company that is easy to work with.

Discovery

Days 1–5

We map your setup, document the gap.

OutputCurrent state audit

Elicitation

Week 1–2

Every endpoint, edge case, business rule confirmed in writing.

OutputWritten spec + fixed price

Build

Week 2+

Dedicated engineers. Weekly demos. Observability from sprint one.

OutputWorking code every Friday

Testing & UAT

Final sprint

Full test suite. Joint validation. Sign-off from both parties.

OutputJoint sign-off

05Live

Go-live

Cutover day

Production deployment monitored by FreySoft. Rollback plan in place.

OutputA system you control

08 / Why FREYSOFT

Why FREYSOFT

Domain depth in regulated fintech

Banking rails, compliance APIs, AML platforms, payment corridors — built in production environments where getting it wrong isn’t an option. No domain ramp-up at your expense.

You own everything

Docs, runbooks, repo — yours from day one. No ongoing dependency on us.

Fixed scope before build starts

We write the spec with you in 1–3 sessions. No homework on your side. Scope creep goes through a change request — it doesn’t happen silently.

Production-grade from sprint one

Error handling, retries, circuit breakers, structured logging — built in from the start. Every integration is built to survive real traffic, rate limits, and 3am schema changes.

Senior engineers on every project

The engineers on the scoping call are the engineers who build. No bait and switch.

Engineering ownership

Our tech director owns every delivery. Not a PM, not a coordinator. An engineer who commits and stays accountable through go-live.

Bad briefs kill more projects than bad engineers.

Most integration projects stall in requirements — not because the tech is hard, but because nobody wrote down what’s actually needed. We do that with you.

1–3 sessions → signed spec
1 week → kick-off after sign-off
48h → written proposal

Start with a scoping session

No SoW from your side. No pitch deck. No follow-up sequence.

Protocols:

RESTGraphQLgRPCWebhooksKafkaProtobuf

Auth:

OAuth2API keystoken rotationIstio service mesh

Payment & Banking:

Banking railsSWIFTSEPAPayment corridors

Compliance:

AML screening APIsKYCSanctions monitoring

Observability:

OpenTelemetryGrafanaStructured loggingElasticsearch

Patterns:

Event sourcingCQRSAsync/syncCircuit breakersRetry logic

FAQ

Currently accepting new clients

Tell us what’s sitting in your backlog.

30 minutes. We’ll scope it honestly – and tell you if we’re not the right fit.

No SoW required. No pitch deck. No follow-up sequence.