Kata

Point your AI at your codebase.
See every diff before it lands.

Kata reads your real solution — up to 21,000+ types across six languages — as a live class diagram. When your AI CLI (Claude Code, Codex, Cursor, or any MCP-compatible tool) proposes a refactor, Kata verifies it: preview the diff, check the policy and quality-delta banners, apply what fits, roll back the rest — all before the source moves. It isn't that the AI is always right. It's that being wrong is cheap here.

  • 6 languages
  • 21k+ types indexed
  • 30+ Fowler refactorings
  • 114 code smells
  • Your AI subscription · no middleman fee
Download Kata for Windows Get Kata Pro →
Kata rendering its own Kata.Cpp namespace — CppCliDeclParser class, CppDeclaration / CppDeclarationSite / CppSpan / CppToken / Implementation records, IEquatable external types implemented via dashed lines, plus 💩 smell badges on parser methods.
Kata dogfooding on its own Kata.slnx — Kata.Cpp namespace: the custom C++/CLI parser, its record model, and the IEquatable implementations that record types get for free.

What Kata changes about your day

Read a codebase you've never touched

Open a real .sln, Maven / Gradle project, tsconfig.json, or go.mod and get an interactive map — Sugiyama layout, namespace clusters, extends / implements edges. You navigate the code before you read it.

Follow a call across language boundaries

Ctrl+Click a member and jump to its definition — even across C# ↔ C++/CLI, TypeScript ↔ types, and Kotlin ↔ Java. Custom parsers per language plus a Roslyn hybrid resolver stitch the graph together.

Six languages, one diagram

C# (Roslyn), C++/CLI (custom parser), Java, Kotlin, TypeScript, and Go — each with its own project loader, symbol resolver, and smell detectors. Mix them in one solution and Kata lays them out together.

Refactor from the diagram, verified before write

Extract Method / Interface / Superclass / Hierarchy, Rename, Move Method, Convert Procedural to Objects — over 30 Fowler intents, invoked on the node you're looking at. Every intent runs through the same preview → apply loop as an AI diff. The same intents are exposed over MCP so external agents ride the same verification path — connect from Claude Code, Codex, or Cursor →

See the smells before you dig

114 smell detectors — Fowler classics (God Class, Long Function, Feature Envy, Message Chains) plus performance, security, and idiomatic wave R checks — surface as 💩 badges right on the class node so you know where to look.

AI proposes. Kata verifies. You apply.

Right-click a 💩 → your AI CLI returns a scoped diff → the policy check and quality-delta banners tell you whether it's safe to keep → apply, or discard with one click. Wrong guesses are cheap here — you see them before the source moves.

Your AI subscription — no middleman fee

Kata never adds an API charge on top. It invokes your local AI CLI — Claude Code, Codex, Cursor, or any MCP-compatible tool — so you keep control of the model, the cost, and which bytes of your code leave the machine.

Runs at real-codebase scale

Verified on VSCode's src/tsconfig.json — 21,464 types indexed, cold render 12.5 s, incremental reloads under a second. When the whole graph is too big to lay out, Kata's scale gate picks the largest namespace that fits and lets you swap views from the top ComboBox.

Real-world scale

Kata was built to survive the codebases people actually work in — not toy samples. On a 21 464-type TypeScript solution (Visual Studio Code's src/tsconfig.json), the whole-graph Sugiyama layout would stall, so Kata's scale gate picks the largest namespace that fits under the layout budget and renders that as the entry view. Switch namespace from the top ComboBox to explore the rest — every type is still loaded, indexed, and Ctrl+Clickable.

Kata rendering a 1157-type subset of VSCode's src/tsconfig.json — dark-themed class diagram with «interface» and «class» stereotypes, auto-picked namespace vs.workbench.api.common.
VSCode (src/tsconfig.json) — 21 464 types indexed, vs.workbench.api.common (1 157 types) auto-selected as the entry view. Cold render 12.5 s.

See it in action

Kata class diagram closeup — MainWindowViewModel class header with a 💩 smell badge in the top-right corner, marking it as a God Class.
Smell badges — 💩 marks every smelly method right on the diagram: long functions, feature envy, message chains, and 20+ more Fowler smells. Class-level smells (God Class, Data Class) get their own badge on the class header.
Extract Superclass refactoring dialog — source class, new superclass name field, and a checkbox list of pull-up member candidates.
Refactor dialogs — Rename, Extract Interface / Superclass / Class, Add Ghost Type, and 25+ more, driven from the diagram surface.
Kata AI diff preview dialog — AI-generated unified diff for MainWindowViewModel.cs, with policy check and quality delta banners above the diff and Apply / Reject / Export buttons below.
AI diff preview — click a 💩, ask your AI CLI (Claude Code, Codex, Cursor, or any MCP-compatible tool), get a real diff with policy check and quality delta before you apply.
Kata with the code viewer pane docked to the right, showing a member's source with breadcrumb and Find References button.
Code viewer pane — Ctrl+Click any underlined member to see its source in place, with breadcrumbs and cross-language jump.

Community and Pro

  Community Pro
License PolyForm Noncommercial (source-available, free for noncommercial use) Commercial (proprietary plugin)
Editor / diagram Full Same base
Fowler refactorings All 30+ All 30+
Code smell badges All 24 smells All 24 smells
View proposed refactors (diff preview) Yes Yes
Apply refactors (30+ Fowler) ★ 14-day free trial, then view-only Unlimited
Cross-language find refs / rename ★ 14-day free trial, then view-only Unlimited
AI diff apply (bring your own AI CLI) ★ 14-day free trial, then view-only Unlimited
Governance report export ★ 14-day free trial, then view-only Unlimited
Team Collab features — Rolling out in 2026
Commercial use Not permitted Permitted

★ The 14-day free trial starts on the first Pro feature use — no signup, no card. After the trial, Community stays a viewer forever. Upgrade any time to keep applying.

See Pro pricing →

Getting started

Download

Grab the latest Community binary or clone github.com/dhq-boiler/Kata.

Open a project

File → Open Solution. Works with C# / C++/CLI (.sln / .slnx), Java (Maven / Gradle), and TypeScript (tsconfig.json).

Refactor from the diagram

Right-click a node or member to open a refactoring, or click a 💩 badge and let AI propose a diff you can preview and apply.