Stop re-explaining your codebase to AI — every session, every tool.
Contexer captures your team's typed engineering decisions — with rationale — once, and replays them into every AI coding session. Reviewed by humans. Consistent across Claude Code, Cursor, Codex, and Gemini.
Stop paying, over and over, to re-establish context your team already has.
Supported agents
- /claude code
- /cursor
- /codex
- /gemini cli
You keep paying to re-create knowledge your team already has.
Onboarding, re-explanation, alignment, and drift look like four separate problems. They're one: every AI coding session — and every new engineer — starts from zero on decisions your team already made.
Kill the AI Re-Explanation Tax
Every session starts with your rules, constraints, and architecture already loaded — so you stop paying the model, in tokens and time, to re-learn what your team already decided.
Onboard humans AND agents instantly
A human onboards once. An AI agent re-onboards cold on every session. Contexer is onboarding-for-agents, every time — decisions and rationale on tap, whether the reader is a new hire or a fresh Claude window.
Align the team without the meeting
One reviewed source of engineering decisions, shared across everyone's AI tools. Knowledge spreads without alignment syncs, and nobody re-agrees on things you already agreed on.
Stop architecture drift
AI can't quietly violate decisions it can see. Approved decisions are enforced across every tool, so drift shows up as a reviewable proposal — not a merged PR three sprints later.
Capture, propose, approve. Right inside your terminal.
These mockups show the intended flow. The actual UI may differ. The idea is decisions captured, reviewed, and replayed where your AI coding assistant already lives.
State a rule. Contexer stores it.
Directives you state outright become global conventions, loaded into every future session.
AI surfaces a decision mid-work.
Architecture and constraint decisions are parked for review, never replayed until you approve.
One keystroke. Versioned forever.
Approve, edit, or ignore. Approved decisions are immutable and replayed across every agent.
Engineering decisions. Not chat history.
"We standardized on PostgreSQL."
"Never expose S3 buckets publicly."
"Terraform modules live under infrastructure/modules."
"Every API emits OpenTelemetry traces."
These are engineering decisions - not chat history, not transcripts, not session logs.
AI memory tools recall conversations. Contexer is your team's decision of record.
CLAUDE.md, AGENTS.md, .cursorrules, and per-assistant memory features are single-player: one person edits a file, another tool ignores it, nothing is reviewed, nothing is versioned. Contexer is the shared layer above them — typed engineering decisions, human-approved, versioned forever, and replayed into every agent your team uses.
Governance is how you keep your AI budget.
Every decision in Contexer is typed, human-approved, versioned forever, and traceable to the session and person that produced it. When finance, security, or the board asks what you're actually getting for your AI spend, you have the receipt: an auditable trail of the decisions your agents are following, who approved them, and why.
It's what teams reach for the moment AI budgets get scrutinized.
Reviewed, not scraped
AI-proposed decisions wait for a human before they're trusted. Nothing enters the team's decision layer without an approver.
Immutable and versioned
Every approved decision has provenance and history. You can answer who decided what, when, and why — down to the session it came from.
Vendor-neutral by design
One decision layer across Claude Code, Cursor, Codex, and Gemini. Your governance isn't locked to whichever model wins next quarter.
Start free. Upgrade when your team grows.
Free
The full decision layer, available two ways. Run the local CLI and JSON store with no account, or sign in for managed cloud sync and the web dashboard.
MIT licensed · No account required for local OSS
Local JSON store. Fully offline. No web app or cloud. No account required.
Encrypted sync, web dashboard, and cross-machine replay.
- ✓Capture architecture, constraint, convention, and pattern decisions
- ✓AI-proposed decisions held for your review
- ✓Approve, edit, skip, or dismiss before replay
- ✓Injected into every Claude Code, Cursor, Codex, and Gemini CLI session
- ✓Web dashboard to review history and manage decisions (Cloud)
- ✓One-click upgrade to Teams
Teams
One repository per team. Invite members and share your approved engineering decisions across everyone's AI coding sessions — one decision of record, every agent. Pricing will be announced once our IP process is settled.
No credit card required · Pricing coming soon
- ✓Everything in Free Cloud
- ✓Unlimited team members with OAuth sign-in
- ✓One shared repository per team
- ✓Shared decision repository via team MCP endpoint
- ✓Role-based approval workflow (lead / member)
- ✓Confidence scores with supporting evidence - leads only
- ✓AI-generated canonical suggestions and updates
Organization
For orgs running multiple teams. One decision layer across every team, with enforcement, drift detection in CI, SSO, and an auditable trail of the AI spend you're defending.
SSO · Audit trail · Pipeline drift detection
- ✓Everything in Teams
- ✓Cross-team decision sharing across the org
- ✓Enforcement policies (require approval, block on drift)
- ✓CI/CD pipeline hook - detects and rates architecture drift on every PR
- ✓SSO login (SAML, OIDC)
- ✓Full audit trail and access controls
- ✓Dedicated support and onboarding
Two commands. Under two minutes.
Requires Python 3.12+ and uv. Auto-detects Claude Code (~/.claude), Cursor (~/.cursor), Codex (~/.codex), and Gemini CLI (~/.gemini) and wires them in.
# Step 1. install $ uv tool install contexer # Step 2. wire into your AI assistant $ contexer install -> detected ~/.claude (Claude Code) -> detected ~/.cursor (Cursor) -> detected ~/.codex (Codex) -> detected ~/.gemini (Gemini CLI) -> wired all four. restart your AI assistant.
Restart your AI assistant and open any git repo. Contexer runs from there.
~26 tokens per rule. Paid once per session.
Approved constraints and conventions are the only thing replayed at session start. Architecture and pattern decisions cost nothing until the work actually needs them, when the agent pulls them on demand. Lookups are sub-millisecond and run before the response is generated — a fraction of the tokens you were spending to re-explain the same decisions by hand.
Deduplication is deterministic - >70% token overlap is dropped. No LLM call. No tokens.
## Project rules - apply to ALL tasks in this repo: - [convention] Use uv, not pip, for all dependency management - [constraint] Never commit untested code - CI blocks merges below coverage 2 architecture decision(s) stored. Call get_context before reading files for questions about architecture or rationale.
Get in touch
Questions, feedback, or partnership ideas - pick the channel that suits you best. We typically respond within one business day.