We take the infrastructure on
Modelion.AI is a product of Mersel Technology, which has been building regulated financial and public-sector software infrastructure in Turkey since 2012. The same team runs the country's e-invoicing infrastructure and Finsel; Modelion is that experience applied to LLMs.
- Mersel founded
- 2012
- data regions
- 3
- languages, equal weight
- 2
- engineering hub
- Istanbul
Why we built this
Mersel has spent more than a decade building systems that get audited. Those systems share a recurring pattern: once a rule is embedded in business logic, changing the rule means changing software — and when an auditor asks why a decision came out the way it did, the answer is scattered across a codebase.
LLMs made that problem larger. Model selection, PII handling, cost, the prompt text itself — all of them are decisions that change quickly and are also subject to audit. Every team that embeds them in application code ends up living with two-week policy changes and audit trails that cannot be reconciled.
Modelion lifts those decisions out of application code and into a single decision point. The engine is not a new invention: OPA is an industry-standard policy engine. Our work was putting it on the hot path of LLM traffic, in a way that stays under a millisecond, and weaving routing, guardrails, prompt management and decision traces around it.
The principles behind our product decisions
Failing open never widens the compliance boundary
When a provider goes down we don't bend a residency rule to keep traffic flowing. With no candidates left, the gateway returns 503. An outage is expensive; regulated data in the wrong jurisdiction is more expensive.
A missing signal is not a clean prompt
Guardrail signals report not only whether something was detected but whether the scan could run at all. If a scanner failed, policy knows, and can choose to be conservative.
A shipped template is a liability
We removed the compliance templates because each carried assumptions that were right for one tenant and quietly wrong for the next. Examples and consulting took their place.
We don't publish what we haven't measured
A policy bundle's evaluation cost is measured at publish time, on the runtime that serves production. A bundle over budget is not distributed — a policy that silently enforces nothing is more dangerous than one that errors.
Losing rules get recorded too
In an audit, "why wasn't this refused" comes up as often as "why was it". The decision trace keeps the winner along with the alternatives that came close.
Two languages, equal weight
Console, documentation and support run equally in Turkish and English. Turkish PII patterns sit in the core of the product, not in a plugin bolted on afterwards.
The Mersel ecosystem
Modelion is part of Mersel's family of infrastructure products. Same team, same operational discipline, same regions.
Let's work together
Seeing the product on your own traffic, or joining the team — same address for both.