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API & System Integration

API / System Integration
Solve "our systems won't talk to each other" — with the right design.
From API gateways and iPaaS to event-driven architecture and legacy integration, we run alongside you on the design and build that connects scattered systems.
Process
01 Integration requirements & current-state survey
02 API / event design
03 Build & test
04 Operations & continuous improvement
Is this you?
We fix the "point-to-point integrations piled up until no one understands the whole"
PAIN 01
Point-to-point integrations have piled up to the point they're unmaintainable
System-to-system integrations were built as isolated points, no one has the full picture, and changing one thing breaks something else.
PAIN 02
Connecting SaaS tools to each other and to core systems still takes a lot of manual relaying
PAIN 03
You want real-time integration but can't make the architecture call
We can step in even when "the integrations have grown beyond what anyone can see."
Tell us what's going on →
The SYSTEMI approach
We build the design that connects scattered systems
Rather than stacking up point-to-point integrations, we select the right integration foundation — API gateway, event-driven, iPaaS, and more.
01
Integration requirements & current-state survey
We take a full inventory of your current integrations and sort out the synchronous vs. asynchronous patterns, update frequency, and data-consistency requirements.
Output
Integration inventory / data flow diagrams / consistency requirements
Output
API design docs / event schemas / OpenAPI / security
02
API / event design
We design the combination that fits the requirements, drawing on API gateways, REST/GraphQL, EventBridge, and iPaaS.
03
Build & test
We build with authentication, throttling, idempotency, retries, and monitoring all included, and use contract tests to guarantee compatibility with the systems you integrate with.
Output
API implementation / contract tests / monitoring / published docs
Output / What happens next
API versioning / deprecation plan / usage monitoring
04
Operations & continuous improvement
We keep it running over the long term, covering API usage monitoring, version management, and deprecation planning.
What sets us apart
Can they see the whole landscape of scattered systems and design the integration foundation?
You need a partner who designs an integration foundation for the whole organization, not one that just stacks up point implementations.
iPaaS vendor Contract dev shop Freelancer SYSTEMI
Whole-system design △ Product-led △ Per project △ Depends on scope ○ From the whole design
API design quality △ Mostly no-code ○ Depends on the project △ ○ OpenAPI / contract tests
Legacy integration △ ○ △ ○ Connecting to existing assets
Operations & continuous improvement ○ Within the platform △ ✕ Out of scope ○ Version management included
AI × Integration
Using AI to lower the cognitive load of integration
Auto-generated API documentation
Claude generates usage examples, SDKs, and documentation from your OpenAPI definition, speeding up onboarding for the teams you integrate with.
Diff & compatibility checks
AI detects the impact of an API change, so breaking changes get reviewed before they reach production.
Natural-language integration queries
Take an integration requirement in plain language — like "notify Slack about Salesforce opportunities" — and generate the iPaaS configuration.
Related cases
Where we make the difference
A mix of published case studies and model scenarios.
G-gen Inc.
API integrationCloud SaaS
We built an integration foundation that aggregates and unifies multiple cloud APIs for G-gen's cloud management SaaS
Challenge
They needed to handle multiple cloud APIs — AWS, GCP, Azure, and more — in a unified way.
Result
An API gateway plus event-driven integration foundation that serves each user exactly the information they need.
MODEL CASE
FDE in action
Model scenarioSaaS consolidation
For a company whose point-to-point SaaS integrations had become chaos, we introduced API gateway consolidation plus iPaaS standardization
Where it started
More than 20 point-to-point integrations were running, and no one had the full picture.
What we untangled
A phased rollout from a full inventory to standardization by integration category to API gateway consolidation.
View all cases →
DELIVERABLES
What we produce on the front line
Sample structures of the documents we actually hand over, organized as decision-ready inputs you can take straight into the next phase.
DOCUMENT 01 — Integration inventory & API design doc
Integration_Spec_v1.0.xlsx
Integration inventoryA list of running integrations with their method, update frequency, and consistency requirements
Data flowHow data moves between systems, plus ownership and consistency
API designOpenAPI definition, authentication, throttling, idempotency, retries
Event designEventBridge / SQS schemas and subscription relationships
Operations policyVersioning, deprecation plan, and usage monitoring
DOCUMENT 02 — Proposed architecture diagram
Example API & integration foundation — Gateway / Event / Integration
Entry point
API GatewayREST / GraphQL
WAF + ThrottlingRate limiting
Cognito / OAuthAuthentication
Synchronous
Lambda / HonoBusiness APIs
Asynchronous
EventBridgeEvent-driven
SQS / SNSQueue / notifications
External SaaS
🔗
iPaaS (Workato)SaaS integration
Monitoring
CloudWatchUsage & errors
Documentation
📘
OpenAPI + contract testsSpec / compatibility
* The API gateway exposes everything in one place, consolidating throttling, authentication, and monitoring.
* Synchronous, asynchronous, and SaaS integration are used as the requirements call for, avoiding a pile-up of point implementations.
FAQ
Common questions about API & System Integration
Should we choose REST, GraphQL, or gRPC?
It depends on the use case. We often recommend REST for public-facing APIs and broad compatibility, GraphQL for complex queries and front-end optimization, and gRPC for internal microservice-to-microservice communication.
Can you put an API in front of a legacy system?
Yes. There are approaches that expose an API via an API gateway or BFF pattern without changing the existing system much. We proceed in stages while guaranteeing data consistency and performance.
Can you also handle external SaaS integration?
We have a track record integrating with the major SaaS used in business — Salesforce, Stripe, Slack, Microsoft 365, and more. We handle it all together, from webhook design and OAuth design to error handling.
How do you handle API versioning and deprecation?
We operationalize a versioning strategy, deprecation notices, and a retirement plan based on Semantic Versioning. We don't abruptly shut down APIs that have active consumers; we retire them with a grace period for migration.
Related services
FDE / Forward Deployed Engineering →
DX Enablement →
Data Platform & Analytics →

If your integrations are in disarray, we start by sorting them out.

Tell us where your integrations stand. We'll run alongside you from the first step of inventory and standardization.

Talk to us about APIs & integration (free)