Context engine for AI coding agents

Your AI agent writes technically correct code that quietly breaks your architecture.

Contexer silently captures every decision your AI makes mid-session and replays them at the start of every future session — so your agent never starts blind.

MIT licensed · Self-hosted · No account required · Claude Code native
· The decay problem

AI agents are brilliant at pattern matching.
Terrible at remembering yours.

01

Documentation rots

READMEs and ADRs lag behind code by weeks. By the time the agent reads them, they're already wrong.

02

Tribal knowledge stays tribal

The reason you don't use that ORM is in someone's head. The agent will helpfully reintroduce it.

03

Rules drift every commit

A new top-level dir, a swapped dependency, a renamed pattern — your CLAUDE.md is stale by Friday.

· How it works

Three steps. No meetings.

01/install

Install in 2 minutes

No account. Works with any git repo.

contexer · install
$ uv tool install contexer
$ contexer install

 installed
 hooked into claude code
 ready
02/work

Work normally

Contexer runs silently. As you work with Claude, decisions are captured automatically — architecture choices, constraints, conventions. Nothing manual.

contexer · work
// session · 14:32
captured: constraint
  "data access goes through
   createServerFn only"

captured: convention
  "Zod schemas live in
   src/lib/schemas.ts"
03/resume

Next session starts with full context

Constraints and conventions are injected before you type anything. Ask a "why" question and the relevant rationale is retrieved automatically.

contexer · resume
// session · resumed
loaded: 14 constraints
loaded: 9 conventions

> why do we use BillingProvider?
↳ retrieved: architecture decision
  "Stripe adapter is migrating,
   use BillingProvider instead"
· What gets stored

Four types of context. Nothing else.

Constraint
Rules that must always apply
✓ Yes
Convention
Team or project standards
✓ Yes
Architecture
Why structural decisions were made
○ On demand
Pattern
Recurring implementation approaches
○ On demand
· Pricing

Start free. No account needed.

Available today

Open Source

Freeforever

Install in 2 minutes. No account. Works with any git repo.

MIT licensed · Self-hosted · No account required

  • Automatic decision capture
  • Session memory across prompts
  • Rationale injection on "why" questions
  • Global conventions store (cross-repo)
  • Works with any git repo
Early access

Teams

Early access

Shared intelligence layer built on top of the open-source engine.

Contact us

Enterprise

Contact us

For platform teams running agents at scale.

· Teams & Enterprise waitlist

The team layer is coming. Get in line.

Prefer the free open-source version? Install it now →