--- title: "Cork vs Crystal: parallel sessions in worktrees, or agents that know about each other · Cork" description: "Cork vs Crystal: Crystal ran parallel Claude Code and Codex sessions in worktrees and is now deprecated. Cork coordinates parallel agents on shared code." canonical: "https://corkcli.com/blog/cork-vs-crystal" last_updated: "2026-11-14" published: "2026-10-03" author: "Kevin Vera" --- # Cork vs Crystal: parallel sessions in worktrees, or agents that know about each other Cork vs Crystal: Crystal ran parallel Claude Code and Codex sessions in worktrees and is now deprecated. Cork coordinates parallel agents on shared code. By Kevin Vera · October 3, 2026 · [Comparisons](https://corkcli.com/blog/c/comparisons) · 7 min read How is Cork different from Crystal? Crystal, by Stravu, was a desktop app that ran multiple Claude Code and Codex sessions in parallel git worktrees so one developer could compare approaches and merge the winners; it was deprecated in February 2026 in favor of its successor, Nimbalyst. Cork is not a session runner: it is a [coordination layer](https://corkcli.com/blog/coordination-layer-ai-coding-agents) that keeps several AI coding agents, and the people running them, from overwriting each other on one codebase, and hands each agent what the others already learned. Crystal kept agents apart by giving each its own worktree; Cork lets agents work on the same code and keeps them aware of each other's changes. If you are looking for a Crystal alternative, the honest answer is that Nimbalyst replaces Crystal, and Cork covers a different gap. ## Cork vs Crystal at a glance | Topic | Cork | Crystal (as of October 2026) | |---|---|---| | What it is | Coordination layer for [parallel AI coding agents](https://corkcli.com/blog/parallel-ai-coding-agents) and teammates | Desktop app for parallel AI coding sessions (deprecated) | | Status | Active | Deprecated February 2026; last release 0.3.5; successor is Nimbalyst | | Where agents run | Where they already run, on your machine | Inside Crystal sessions, each in its own git worktree | | Agents covered | Claude Code, Codex, Cursor (hooks); any MCP client | Claude Code and OpenAI Codex | | Who it serves | Several agents and several people on one codebase | A single developer comparing sessions | | Conflict handling | Write gate, live change notices, [semantic lint](https://corkcli.com/blog/semantic-lint), rebase-and-test landing | Worktree isolation, then merge or rebase to main | | Install | `curl -fsSL https://corkcli.com/install.sh \| sh` | Desktop download (macOS, Linux, Windows); downloads now point to Nimbalyst | | Open source | See corkcli.com | Yes, MIT | | Pricing | Free (local, and 10 agent hours a month in the cloud); $20 a month per 100 agent hours, pooled | Free, open source | ## What is Crystal? Crystal's GitHub repository describes it as a way to "run multiple Codex and Claude Code AI sessions in parallel [git worktrees](https://corkcli.com/blog/git-worktrees-parallel-ai-coding-agents). Test, compare approaches & manage AI-assisted development workflows in one desktop app." It is MIT licensed. Its release notes list the workflow features: merging and rebasing a session to the main branch, "merge and archive," git status indicators, a diff viewer, run scripts with a logs panel, a terminal, and, from version 0.3.4, multiple agent panels per session. Releases were published for macOS (including Homebrew), Linux and Windows. The repository now states that Crystal "has been deprecated and replaced by Nimbalyst." The last release, 0.3.5 (February 26, 2026), recommends migrating, though Crystal remains usable without further updates. Nimbalyst, the successor, describes itself as an AI-native workspace that keeps git worktree isolation for parallel AI coding sessions and adds editors for code, markdown, spreadsheets and diagrams. ## What is Cork? Cork (corkcli.com, by Lithometric) keeps several AI coding agents, and the people running them, from overwriting each other on one codebase, and hands each agent what the others already learned. It does not run agents or host machines: Claude Code, Codex and Cursor keep running where they already run, and Cork coordinates them. Hooks in Claude Code, Codex and Cursor do the protocol with no extra model calls, and an MCP server (https://mcp.corkcli.com) serves any MCP client. Each agent gets a briefing with the exact signatures, callers and recent changes of the code it is about to touch. When another agent renames something yours depends on, your agent hears it on its next step. A [write gate](https://corkcli.com/blog/write-gate) holds an edit against code another agent is changing right now until your agent has their version. Semantic lint turns a teammate's rename into a rule your agents are checked against. Landing turns `git push` into one step that rebases onto teammates' commits, reruns the tests and pushes. Agents can message each other, and MCP tools include get_symbol, blast_radius, recap and remember/recall. ## Where Crystal stands out - **Simple mental model.** One session, one worktree: agents cannot touch each other's files while they work. - **Built for comparing approaches.** Running several sessions on the same task and picking the best diff was Crystal's core use case. - **A full visual workspace.** Diff viewer, terminal, run scripts and logs in one desktop app. - **Open source and cross-platform.** MIT licensed, with builds for macOS, Linux and Windows. - **A maintained successor.** Nimbalyst carries the worktree approach forward for people who liked Crystal. ## Where Cork wins - **It is actively developed.** Crystal no longer receives updates. - **Worktrees still meet at merge time.** Crystal's isolation postpones conflicts until you merge or rebase. Cork tells agents about each other's changes while they work and gates edits to code another agent is changing, so agent merge conflicts are prevented rather than discovered. - **Teams, not just one developer.** On the paid plan, agents on teammates' machines see each other, which a single-user desktop app does not attempt. - **Agents arrive informed.** Briefings hand agents the signatures and callers they need. In Cork's benchmark (12 Claude Code agents at once on one repository, hard tasks), agents with Cork used 53% fewer tokens than without it. - **No new app to live in.** Cork works with Claude Code, Codex and Cursor where you already run them. ## Can you use both? Technically yes, but with Crystal deprecated we would not start a new setup on it. The useful pairing today is a worktree-based session manager (such as Nimbalyst, Crystal's successor) with Cork underneath: the session manager keeps agents' files apart and gives you a UI, and Cork keeps those agents aware of each other's renames and signature changes so their branches still fit together. Cork does not provide a code editor, terminal UI or diff viewer, so it does not replace that layer. ## Pricing compared - **Crystal:** free and MIT licensed. Its downloads now point to Nimbalyst. We did not evaluate Nimbalyst's pricing for this comparison. - **Cork:** Cork Free gives unlimited agents and repos on one machine, no account, all data on the machine. Cloud Free adds an account with 10 agent hours a month (30 bonus hours the first month) and a 30-day history window. Beyond that you pay for agent hours, not seats: $20 a month per unit of 100 hours, pooled across the workspace, graduated to $17 (units 11 to 50) and $15 (51 and up), with 15% off a year. Every member is a player, with teammates' machines, prompts matched to code by meaning, shared knowledge and 90-day history. Enterprise starts from about 100 units. ## Bottom line Crystal popularized running parallel Claude Code sessions in git worktrees, and its successor Nimbalyst continues that idea. Worktrees keep agents from overwriting each other's files, but not from writing changes that conflict when merged. Cork addresses that gap by coordinating agents live on shared code, across one machine or a whole team. If you are replacing Crystal, pick a session manager for the UI and consider Cork for coordination. ## Frequently asked questions ### Is Crystal still maintained? No. As of October 2026, the Crystal repository says it was deprecated in February 2026 and replaced by Nimbalyst. The last release was 0.3.5. ### Is Cork an alternative to Crystal? Partly. If you used Crystal to run multiple Claude Code agents in parallel, Cork does not run or display sessions. It coordinates the agents you already run so they do not collide. Nimbalyst is the direct replacement for Crystal's app. ### Did Crystal stop agents from overwriting each other? Crystal put each session in its own git worktree, so agents could not edit the same files at the same time. Conflicts could still appear when sessions were merged or rebased onto main. ### Which agents did Crystal support? Claude Code and OpenAI Codex. ### Is Crystal free? Yes. Crystal is free and MIT licensed, though it no longer receives updates and its download links now point to Nimbalyst. ## Sources Checked October 2026: - - - - ## Related reading - [Cork vs git worktrees: separate folders, or agents that know about each other](https://corkcli.com/blog/cork-vs-git-worktrees): Cork vs git worktrees for parallel AI coding agents: worktrees isolate files while agents work, Cork coordinates them so the work still fits at merge. - [Cork vs Xirp: run many agents, or keep many agents from colliding](https://corkcli.com/blog/cork-vs-xirp): Cork vs Xirp: Spotify's Xirp runs parallel coding agent sessions in worktrees on macOS. Cork coordinates those agents so they stop overwriting each other. - [Cork vs Claude Code on the web: where agents run, or how they share one codebase](https://corkcli.com/blog/cork-vs-claude-code-on-the-web): Cork vs Claude Code on the web: one runs Claude Code sessions in Anthropic's cloud, the other keeps parallel agents from colliding on shared code. - [Cork vs Mosaic: shared session memory, or live coordination on the code](https://corkcli.com/blog/cork-vs-mosaic): Cork vs Mosaic: Mosaic syncs AI coding sessions into shared team memory; Cork keeps parallel agents from overwriting each other. How they differ and fit. [All articles](https://corkcli.com/blog.md) · [Cork in Markdown](https://corkcli.com/index.md) · [llms.txt](https://corkcli.com/llms.txt) This page in HTML: https://corkcli.com/blog/cork-vs-crystal