Insurance teams can turn Excel-based rating models into governed, production-ready APIs without rewriting logic or replacing existing workflows.
That’s the practical shift happening across underwriting, actuarial, and product teams. Excel still holds critical pricing and risk logic. The challenge isn’t the models themselves—it’s that they’re isolated, manually updated, and difficult to integrate or govern at scale.
By exposing Excel models as APIs, insurers can execute the same trusted logic consistently across underwriting workbenches, broker portals, and core systems—while maintaining version control, auditability, and test coverage.
This is the role Coherent Spark plays.
Why Excel-Based Models Become a Bottleneck
Most insurance rating models still live in spreadsheets for good reason. Excel allows domain experts to iterate quickly, document assumptions transparently, and respond to market or regulatory change.
But once those models need to be shared across systems, teams run into familiar problems:
- Manual data handoffs and re-keying
- Unclear ownership of “approved” versions
- Limited visibility into how logic changes affect downstream behavior
- Testing and compliance checks that happen late, if at all
The result isn’t just inefficiency. It’s execution risk.
From Excel Workbook to API
The process starts with a typical Excel workbook.
Take, for example, a Cyber Insurance Rater used for pricing policies. This file contains all the business logic, calculations, and formulas needed to generate premiums. But in its current form, it exists in isolation, requiring manual input and suffering from governance gaps.
Using Excel’s Name Manager, model authors define input and output cells by tagging them with simple, explicit naming conventions. Inputs might include state or coverage limits. Outputs might include premium tables or pricing components. This step ensures that every relevant variable in the model is explicitly labeled for API conversion.
Once uploaded to Coherent Spark, the platform:
- Extracts the calculation logic directly from the workbook
- Translates it into production-ready code
- Exposes the model as a callable API
The underlying Excel file remains the source of truth.
What changes is how—and where—that logic can be executed.
Watch how this transformation happens in real-time:
Governing Rating Logic Like Source Code
Turning a model into an API is only useful if it can be managed safely over time.
Coherent Spark applies software-style governance to Excel-based logic:
- Every update creates a new version
- Previous versions remain available for audit and comparison
- Changes are traceable back to the originating workbook
For example, adjusting a base rate for a specific state results in a new API version rather than overwriting what was previously live. Teams can review exactly what changed and understand its downstream impact before deployment.
This is how rating logic becomes observable and defensible—without forcing actuarial or underwriting teams out of Excel.
See how versioning and governance work in action:
Testing and Compliance at Scale
Before changes go live, insurers need confidence that models behave as expected.
Coherent Spark’s Test Bed enables teams to generate large volumes of test cases automatically, using the same validation rules already defined in Excel.
This makes it possible to:
- Stress-test models across realistic input combinations
- Detect unexpected pricing behavior early
- Maintain a historical record of inputs, outputs, and API calls
Testing becomes part of the workflow, not a last-minute checkpoint.
Beyond Rating Models
While rating is often the starting point, the same pattern applies to other Excel-based logic across insurance operations—rules engines, commissions, taxes, reserving, and more.
Because models can call one another and pull in real-time external data, insurers can incrementally modernize execution without rewriting proven logic or centralizing everything into monolithic systems.
Excel stays where expertise lives.
Execution moves to where scale and governance are required.
