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Business logic is trapped in your codebase

Every application has rules — approval thresholds, pricing tiers, eligibility checks, routing logic. Right now, those rules are scattered across your services.

CLI-first decision infrastructure

BDL is an open format. Rules can be generated, converted, or edited locally. Test against unit cases or real-world data. Publish to Sertainly's hosted runtime. Evaluate via REST or MCP.

See it: a decision rule in BDL

This is what a BDL rule looks like — whether generated from a document, converted via the CLI, or written by hand. Publish it, and get a deterministic verdict from the API.

- id: MEAL_LIMIT_CHECK
  type: LIMIT
  priority: 100
  applies_when:
    eq: [expense.category, MEAL]
  rule:
    field: expense.amount
    max: 75
    per_person: true
    basis: expense.attendees_count
  outcomes:
    on_apply:
      verdict: compliant
      reason_code: MEAL_UNDER_LIMIT
    on_breach:
      verdict: non_compliant
      reason_code: MEAL_OVER_LIMIT

// POST /v1/evaluate
// expense.amount=185, attendees=3
// 185 / 3 = 61.67 < 75 per person

{
  “verdict”: “compliant”,
  “reason_codes”: [“MEAL_UNDER_LIMIT”],
  “derived”: {
    “per_person_amount”: 61.67
  },
  “trace_id”: “tr_8f2a…c3d1”
}

Why not just hardcode the rules?

You could. But here's what happens at scale.

The BDL language

A decision package is a set of statements. Each statement is a typed rule with a priority, conditions, and deterministic outcomes. Six statement types cover the full range of business logic.

The five verdicts

Every call to /evaluate returns exactly one verdict. The verdict is deterministic — same input produces the same output on every call.

Deterministic means testable

Because every evaluation is a pure function of rules + case data, decision packages are fully testable. srt test runs unit tests against individual statements.srt test <file> runs batch evaluation against real-world data for simulation, regression, and CI verification. Same rules, same data, same verdict — locally, in CI, and in production.

Do I have to learn another rules language?

Not really. BDL is designed for generation, not manual authoring.

Most teams start with a source document — a policy PDF, a compliance spec, a spreadsheet of business rules. Run srt convert and BDL is generated for you, along with test cases. You review the output, run the tests, and publish. If you need to tweak a threshold or add a condition, BDL is readable YAML — but you rarely start from a blank file.

BDL exists so that business logic has a deterministic, testable representation that lives outside your application code. Without it, rules end up in if statements scattered across services, or in LLM prompts where they're neither versioned nor reproducible. BDL gives rules a home: versioned artifacts that can be validated locally, tested in CI, and executed identically in production.

From zero to verdict in 5 minutes

Install the CLI. Convert a document. Test. Publish. Evaluate. No SDK required — if you can curl, you can integrate.

Plans

Decisions are billed per evaluation. AI features use separate credits. Start free, scale when you need to.