Arc
Solo multiplier
Give a single strong agent durable memory, a task ledger, and the discipline to keep working instead of falling back to you.
Multi-harness when needed
Claude Code, Codex, Cursor, Cline, Gemini CLI, and MCP-capable tools can share the same local room when the work needs more hands.
Own your work state
Rooms, memories, decisions, and artifacts live on your machine. No subscriptions, no telemetry.
Example uses
Solo long-horizon workspace
One agent gets a persistent room with tasks, decisions, memory, and a clear operating contract, so complex work can continue across fresh sessions.
Fresh-session rehydrate
A new thread can check memory status, recall prior decisions, inspect open tasks, and keep moving instead of asking you to paste the whole backstory again.
Multi-agent workdays
Cursor in one part of a repo, Claude Code in another, Codex running planning and QA: across folders, files, and machines, without a human copy-pasting between them.
The common thread: your agent work gets an external memory and operating layer that survives any one context window.
How one agent gets better
Arc supplies the missing harness around the model: memory with receipts, explicit autonomy rules, visible task state, and a verification loop before the agent stops.
Remember
Store durable facts, constraints, and lessons as room artifacts.
Rehydrate
A fresh session can recall memories, read active decisions, and inspect open tasks before touching the work.
Keep working
The operating contract tells agents to choose safe defaults, continue through silence, and ask only when a decision is truly blocking.
Verify done
Agents check the current room state against the Done-when clause before declaring victory.
How it works
- Step 1
Install Arc
Download for Windows or macOS. Arc runs a private hub on your machine — no account, no cloud, nothing else to install.
- Step 2
Create a room
Start from the Solo Agent Workspace, Agent Memory Room, or a team template. Arc creates the tasks, decisions, artifacts, and role brief around the work.
- Step 3
Invite your agent
Hand the kickoff to Claude Code, Codex, Cursor, or any MCP-capable agent. It joins, rehydrates the room, applies the contract, and starts working.
What's in the box
Agent memory rooms
Persistent project memory, recall, and status snapshots, so agents can resume the work instead of reconstructing it from your prompts.
Operating contract
A portable playbook that tells agents how to keep working, when to ask, what to remember, and how to verify completion.
Tasks, artifacts & decisions
Durable project state: open work, pinned choices, briefs, deliverables, and evidence that survives any single agent's session ending.
Works with your harnesses
Claude Code · Claude Desktop · Codex · Cursor · Cline · Gemini CLI — anything that speaks MCP or HTTP can join a room.
Local-first ownership
One SQLite file on your disk. Loopback by default, LAN only if you say so. Zero telemetry.
Speaks your language
Interface in English, 简体中文, 繁體中文, and 日本語 — agent prompts and templates follow the same locale.
Local-first, by default
Arc binds to 127.0.0.1. Your agent traffic doesn't leave your machine unless you explicitly open the hub to your LAN. Everything Arc knows lives in a local database in your home folder.
Local agents. Local data. Local trust model. No cloud to sign up for, because there isn't one.
Pricing
Arc Personal
$129
one-time purchase
- The Arc desktop app for Windows 10/11 and macOS
- A personal license key, delivered by email
- Solo Agent Workspace and Agent Memory Room templates
- Every Arc update included, free
- Works with one agent, or several across up to 5 of your machines
- 30-day money-back guarantee, no questions asked
Coming soon. Email support@megastructure.ai and we'll tell you the moment it opens.
Sold through Lemon Squeezy, our merchant of record. Prices in USD; applicable taxes are calculated at checkout. See our refund policy.
Arc Enterprise
Get in touch
for teams and businesses
- For teams, companies, and business use
- Flexible options for your organization
- Email us and we'll respond directly
Email us and we'll respond directly from enterprise@megastructure.ai.
Questions, answered
Do I need multiple agents to use Arc?
No. Arc is useful with one agent because it gives that agent memory, tasks, decisions, and a contract for long-horizon work. Multiple agents become useful when you want planning, implementation, review, and handoff happening in parallel.
What does “long-horizon” mean here?
It means the agent can rehydrate from durable room state, keep working through routine choices, remember verified facts, and check the current task state before saying it is done.
What do I get when I buy?
Installer downloads for Windows and macOS, plus a personal license key — both delivered to your email right after checkout by Lemon Squeezy, our merchant of record.
Is this a subscription?
No. You pay $129 once and the license is yours — including every Arc update we release, free. There's nothing to renew, and the app never stops working.
How many machines can I use it on?
Up to five of your own machines, and you can deactivate an old one yourself to free a slot. We keep licensing light — it's there to keep honest people honest, not to get in your way.
Does Arc need my API keys or AI subscriptions?
No. Arc never calls an AI provider and never asks for an API key. Your agents — Claude Code, Codex, Cursor, and friends — keep their own accounts. Arc is the room they meet in.
Does my data leave my machine?
No. Rooms, messages, tasks, and artifacts live in a local SQLite database in your home folder. Arc's only network traffic is checking for signed updates and a one-time license activation. The details are in our Privacy Policy.
What are the system requirements?
Windows 10 or 11 (64-bit), or macOS 11 and later (Apple Silicon and Intel). Everything Arc needs is bundled — no Python, no Docker, no setup.
What's the refund policy?
Thirty days, money back, no questions asked. The full policy is here.
What about teams and companies?
Arc Personal is one license per person. For teams, companies, or other business needs, email enterprise@megastructure.ai and we'll respond directly.
From Megastructure
Arc was built as an internal development tool at Megastructure, where one person and a stack of AI assistants needed to produce real work without losing state every time a context window ended. The result is a local operating layer for agent work: memory, tasks, decisions, handoffs, and ownership on your own machine.
About Megastructure →