Def Code · CLI

A senior engineer
in your terminal.

Def Code is a command-line AI developer built for real codebases. Four purpose-built modes — Plan, Build, Design, Test — for the way engineers actually work. Scoped, reviewable, and dramatically cheaper than the alternatives.

Install Def Code Read the docs
Plan · Build · Design · TestRepo-aware
~/stripe-dashboard Plan mode
→ def plan "add stripe refund webhooks"
Reading codebase · 412 files · 28 packages
Framework: Next.js 14 · Drizzle · Vitest
Style: pnpm · eslint-airbnb · strict ts

Proposed plan · 4 steps
├─ routes/webhooks/stripe.ts new · handler
├─ lib/stripe/signatures.ts new · verify
├─ db/schema/refunds.ts new · migrate
└─ tests/webhooks.test.ts new · 6 cases

Estimated: 340 LOC · 4 files · 0 breaking changes

→ proceed? [Y/n]
Four purpose-built modes

Think, build, design, test.

Most AI coders have one mode: generate. Def Code has four, because real engineering has phases. Each mode is tuned for the work it's doing.

def plan

Plan

Reads your repo, analyzes the framework and conventions, proposes a scoped plan. No file touched until you approve.

scoped · reviewable · safe
def build

Build

Writes the actual code. Follows your lint rules, patterns, and typing. Opens a PR you review like any other.

style-aware · PR-ready
def design

Design

UI flows, component scaffolds, architecture diagrams. Turns "I need a settings page" into real code, not Figma.

UI · components · flows
def test

Test

Generates unit, integration, and e2e tests with meaningful assertions. Covers the corners you forget.

unit · integration · e2e
Repo-aware, always

It reads your code before it writes.

Def Code indexes your entire codebase — your framework choices, naming conventions, test patterns, even your commit style. Then it writes like someone who's been on your team for a year.

  • Full-repo embeddings, branch-aware
  • Respects your eslint, prettier, tsconfig
  • Follows existing file structure
  • Commits with your team's message style
~/monorepoBuild mode
→ def build
Applying plan · step 1 of 4
✎ routes/webhooks/stripe.ts +87 -0
✎ lib/stripe/signatures.ts +42 -0
✎ db/schema/refunds.ts +18 -0
Running eslint · prettier · tsc…
✓ lint clean · types pass · 0 new warnings

✓ branch feat/stripe-refund-webhooks
✓ pr #248 opened · 3 files · +147
→ review diff? [Y/n]
Test mode · the real killer feature

The tests you keep meaning to write.

Point Def Code at a file, a module, or a legacy service. It generates meaningful tests — not just coverage theatre — and tells you the weak spots it can't reach.

  • Unit, integration, and Playwright e2e
  • Meaningful assertions, not "expect truthy"
  • Identifies untestable code and suggests refactors
  • Runs your suite and iterates until green
~/monorepoTest mode
→ def test lib/billing/
Scanning 14 files · generating tests…
✓ proration.test.ts · 12 cases · 9 edges
✓ refunds.test.ts · 8 cases · 3 edges
✓ invoices.test.ts · 14 cases · 5 edges
⚠ taxes.ts · untestable · see note below

Running vitest…
✓ 34 passed · 0 failed · 890ms

note: taxes.ts imports runtime-only dependency;
suggest extracting pure fn to lib/billing/tax-math.ts
→
The price part

Premium quality. Paperback price.

Other AI coders bill like infrastructure. Def Code bills like software. Same output quality, a fraction of the monthly run-rate.

Typical AI coding agent
The other guys
$200/mo
  • One mode: generate
  • No repo awareness by default
  • Pay-per-token on top of seat
  • Limited test generation
Def Code
Included · Pro & above
$29/mo
  • Four modes: plan, build, design, test
  • Full-repo indexing on every run
  • Flat monthly credits, no surprises
  • Test mode is a first-class citizen
→npx definable/def-code init copy

Ship faster. Sleep more.

Install Def Code in 30 seconds. Works with any language, any framework.

Get Def Code Back to overview