Synapse vs Nimbalyst

At a glance

Nimbalyst facts are from nimbalyst.com, its pricing, docs and GitHub repo, plus the Crystal repo, checked on 16 October 2026.

From Crystal to Nimbalyst

Crystal, from Stravu, was a popular open-source app for running Claude Code and Codex sessions in parallel, each in its own git worktree. It was deprecated in February 2026. The final release is v0.3.5 from 26 February 2026, and the README now reads "Crystal Is Now Nimbalyst". You can keep using Crystal, but it will not be updated.

Crystal had no agent-to-agent features. If you are looking for a Crystal alternative, Nimbalyst is the official path. Synapse is a different option if what you mainly want is parallel agents that know about each other.

What Nimbalyst is

Nimbalyst describes itself as "the open-source visual workspace for building with Codex, Claude Code, OpenCode, and other coding agents." You run parallel sessions, optionally in worktrees, and edit markdown, mockups, Mermaid, Excalidraw, CSV and code in WYSIWYG editors where agent changes show as red and green diffs you accept or reject. It adds a session kanban, trackers, git with PR reviews, extensions and an iOS app. Teams, in beta, adds real-time shared docs and trackers.

It went open source around late April 2026 and ships very often: v0.81.6 came out on 15 October 2026.

What Synapse is

Synapse is only about the connection between agents. It puts every live coding agent on your machine on one canvas. Drag from one agent to another and the second one sees what the first is doing. On each prompt, a hook injects what the linked agent said since last time, up to 8,000 characters per link. Any two linked agents can message each other through six MCP tools, a CLI and a skill.

synapse peers
synapse link amp-docs
synapse send amp-docs "The API now returns 409 on duplicate slugs."

How Nimbalyst and Synapse connect agents

This is the closest overlap of any workspace we have compared.

Nimbalyst:

• Meta Agent (alpha toggle). An orchestrating session gets internal MCP tools: spawn_session for child sessions, send_prompt, consume_session_inbox for reports from children, get_session_result and respond_to_prompt to answer a child's questions. It works with Claude Code and Codex sessions, and Gemini can be a meta-agent provider.
• Session-context tools, any session. get_session_summary, get_workstream_overview and list_recent_sessions let an agent pull a compact summary of another Nimbalyst session when it asks.
• Blitz (alpha). Runs one prompt across up to 10 worktrees with chosen models, then creates an analysis session that compares the results.

All of this is scoped to sessions Nimbalyst created or imported. The model is a parent driving children, or an agent pulling a summary on demand.

Synapse:

• Peer links you draw. No agent is in charge. A link from A to B means B gets A's new conversation on every prompt, automatically. Draw both ways for a pair.
• Any tool, any vendor. Synapse finds agents by scanning processes and their working folders, so an Amp agent in a plain terminal can be linked to a Codex agent in tmux.
• Pull, not push. Messages are seen on the next prompt or through synapse_inbox. A Nimbalyst Meta Agent can actively drive and answer its children; Synapse cannot wake an idle agent.

Token usage

In July 2026 a GitHub issue titled "Nimbalyst extremely token-greedy" (#889) reported that two meta-agents used 75% of a Claude Max 20x five-hour limit in under an hour. Karl Wirth from Nimbalyst replied that a prompt-cache invalidation bug was fixed in 0.70.5. Another user later reported heavy usage on 0.70.5, so whether the fix fully solved it is unclear from the thread.

Synapse adds at most a capped context injection per link per prompt, set by SYNAPSE_BUDGET, and runs no agents of its own.

Open source, accounts and privacy

Nimbalyst's desktop and iOS apps are MIT. Individual use needs no account. It sends anonymous PostHog analytics by default, which you can turn off in Settings, and its README says that excludes file contents, paths, keys and chat content.

Synapse is MIT with a zero-dependency Node core, no account and no network calls.

Where Nimbalyst is ahead

• A much broader product. Visual editors with diff review, trackers, kanban, git and PR tools, mobile apps with push notifications, voice, extensions, and Windows and Linux support. Synapse has none of this.
• Active orchestration. A Meta Agent can spawn, prompt, wait on and answer its children, and Blitz compares models automatically. Synapse's messages are pull-only.
• Multiplayer you can use today in the Teams beta. Synapse's multiplayer is in development.

If you want one visual workspace for plans, docs and agents, Nimbalyst is the stronger choice.

Using Synapse with Nimbalyst

Synapse discovers CLI agent processes wherever they run. That should include sessions Nimbalyst runs on the genuine Claude Code CLI or Codex as normal processes, but we have not verified it, and its built-in Claude Agent SDK provider may not appear as a normal Claude Code session.

1. Keep Nimbalyst for editors, trackers and parallel sessions.
2. Install Synapse: node install.mjs && npm start.
3. Check which Nimbalyst sessions show up on the Synapse canvas.
4. Link one to an agent Nimbalyst does not run, such as Amp or Gemini CLI in a terminal.
5. Use the Meta Agent inside Nimbalyst and Synapse links for agents outside it.

Who should pick which

• Pick Nimbalyst if you want Crystal's successor: a full visual workspace with parallel sessions, editors, trackers, mobile and team features.
• Pick Synapse if your agents run in many tools, you want peer links instead of a parent agent, or you want no login, no telemetry and no network calls.
• Run both if you live in Nimbalyst but also run agents outside it.

FAQ

Is Crystal for Claude Code deprecated?

Yes. Stravu deprecated Crystal in February 2026. The final release is v0.3.5 from 26 February 2026, and the README says Crystal is now Nimbalyst. It still runs, but it will not be updated.

What is the best Crystal alternative?

Nimbalyst is the official successor and the closest replacement, with parallel sessions and worktrees plus much more. If you mostly want parallel agents that share context, a simple worktree tool paired with Synapse is a lighter option.

Is Synapse a Nimbalyst alternative?

Partly. Synapse links and messages agents in any CLI, with no login. It does not replace Nimbalyst's editors, trackers, git tools or mobile apps.

What is the Nimbalyst Meta Agent?

An alpha feature where an orchestrating session gets tools to spawn child sessions, send them prompts, read their results and answer their questions. It works with Nimbalyst's own Claude Code and Codex sessions. Synapse instead links independent agents as peers.

Does Nimbalyst use a lot of tokens?

Issue #889 reported meta-agent setups using most of a Claude Max five-hour limit in under an hour. Nimbalyst said a prompt-cache bug was fixed in 0.70.5, though a user still reported heavy usage on that version.

Does Synapse see agents running inside Nimbalyst?

It should, for sessions Nimbalyst runs as normal Claude Code or Codex CLI processes, because Synapse finds agents by process scan. We have not verified this, and sessions on Nimbalyst's built-in SDK provider may not show up.