Stop negotiating feature requests. See every behavior at any depth, direct changes in plain English, ship in hours instead of months.
From black-box codebase to living behavior map in under 2 hours.
The Problem
Most SMBs with custom software face the same trap: the codebase is a black box. Business rules are buried. Changes are slow and risky. You're paying to maintain something you can't understand.
Nobody can explain what the software actually does. Business rules are buried in code that only the original developer understood.
The developer who built it left. The agency moved on. Critical business logic lives in one person's head -- or nowhere.
Every change is scary. Nobody knows what will break. Small feature requests take weeks. Innovation stalls.
The agency controls the relationship because you can't see or independently modify your own software. You pay $50K-$200K/year without knowing what you're getting.
The Insight
"Code is a compilation target.
Behavior is the source code."
Your software already has behavior -- screens, workflows, business rules, data models. It's just invisible, buried in thousands of lines of code. Terso surfaces it and gives you a continuous interface to understand, change, and verify it.
| Era | Problem | Solution |
|---|---|---|
| 2000s | Can't see infrastructure | Monitoring (Datadog, New Relic) |
| 2010s | Can't see errors | Error tracking (Sentry, Bugsnag) |
| 2020s | Can't see code quality | Static analysis (SonarQube) |
| 2026 | Can't see behavior | Terso |
How It Works
Point Terso at your codebase. Get a living behavior map at every level of detail -- from system architecture down to field-level logic. Direct changes in plain English. Code recompiles deterministically.
Why Terso
See what your software does -- not just how it's written. A living behavior map that evolves with your application.
Point Terso at any codebase. AI analyzes routes, components, data models, and business rules. Get a structured BehaviorScheme in hours, not weeks.
Not a static diagram or a one-time report. The BehaviorScheme evolves with your software. Ask questions, direct changes, verify results -- all through natural language.
A non-technical stakeholder can review the behavior map and understand what the software does. No code reading required.
Same scheme, same code. React frontend, Hono/Drizzle backend, Playwright/Vitest tests -- all derived deterministically from one source of truth.
The BehaviorScheme is diffable, versionable, and survives model upgrades. When Claude 5 or GPT-5 arrives, your behavior specs don't change. Only the analysis improves.
Three-dimensional quality signal -- completeness, consistency, compilability -- evaluated before generation. Know if your behavior map is accurate before code is touched.
Positioning
Agencies give you a PDF. Code analysis tools give you metrics. Terso gives you a living behavior map and a continuous interface to evolve your software.
| Dimension | Agency Assessment | Code Analysis (SonarQube) | Terso |
|---|---|---|---|
| Output | PDF report, stale on delivery | Code quality metrics | Living behavior map |
| Frequency | Point-in-time | Continuous (code-level) | Continuous (behavior-level) |
| Audience | Technical | Technical | Technical AND non-technical |
| Actionability | Recommendations | Alerts | Understand, direct, and verify changes |
| Cost | $10K-$50K per engagement | $300-$2K/mo | $500-$2K/mo per app |
| Generates code | No | No | Yes -- deterministic |
The Founder
"I spent my career being the bridge between business people and software. I've done manual codebase assessments for SMBs -- reading someone else's codebase, documenting what it does, explaining it to the business owner. That process costs $10K-$50K and produces a PDF that's outdated the day it's delivered."
"Terso automates the work I've done my entire career -- giving businesses a living, readable map of their software."
-- Stephane Marin, Founder
Built For
You built or commissioned custom software. It runs your business. But you can't see what it does. Terso changes that.
You own the software but can't see inside it. You're paying $50K-$200K/year to maintain something you don't understand. Terso gives you a readable map and the confidence to direct your own software.
You inherited a codebase with no documentation. Every feature request requires archaeology. Terso gives you behavior-level understanding and a pipeline to make changes safely.
Onboarding takes months because nothing is documented. You're afraid to touch half the codebase. Terso gives your team living documentation and confidence to ship.
Changelog
Terso is under active development. Here's what we've built recently.
Import codebases written in TypeScript, Swift, Python, Go, Ruby, and Rust. The AI analysis pipeline now handles language-specific patterns (SwiftUI views, Django models, Go handlers) and produces framework-aware BehaviorSchemes.
Export any BehaviorScheme as a structured Product Requirements Document. Fifth compilation target alongside React, Hono API, Playwright, and Vitest.
Adversarial reviewer that identifies missing error paths, unused entities, dead-end states, and data inconsistencies in your BehaviorScheme before compilation.
Full undo/redo for scheme mutations. AI-proposed changes go through a staging buffer with visual diffs before being committed. Accept, reject, or modify individual mutations.
Design Partner Program
We're accepting 5 founding design partners. Get full platform access at no cost. Help us build the future of software intelligence for SMBs.
3 of 5 spots remaining. No cost during the program.