jcode

The most RAM efficient harness The most intelligent harness

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Installation

# macOS & Linux
curl -fsSL https://jcode.sh/install | bash

# Windows 11 (PowerShell 5.1+)
irm https://jcode.sh/install.ps1 | iex

Need Homebrew, source builds, provider setup, or want an agent to set it up for you? Jump to detailed installation.

Updating

Run /update in the TUI to download the latest stable release in the background and reload with your session preserved. From a terminal, use jcode update, then restart the client. Both commands use the same update policy, including for dev builds.

Older or equal release versions are skipped. For a development build, Jcode also compares the running binary's Git commit with the release tag. Builds ahead of, identical to, or diverged from the release are preserved. If ancestry cannot be verified locally or through GitHub, the update stops rather than risking a downgrade. The displayed dev patch includes a commit-count offset, so it is not used as a release version comparison.

This is the default features.update_channel = "stable" behavior. An explicit "main" channel still opts into source-branch updates. Use /rebuild or the self-dev build workflow to rebuild your own checkout.

Performance & Resource Efficiency

jcode is built to be as performant and resource efficient as possible. Every metric is optimized to the bone, which is important for scaling multi-session workflows. Here we sample a few metrics to show the difference: RAM usage and boot up.

RAM comparison

Headless sessions (swarm workers)

Swarm workers run headless, so this is the number that matters when you fan out agents. Each session completed 5 real model turns (file listing, file read, repo search, summary, reply) with tool calls, then total PSS of every process was measured. jcode sessions share one daemon; Claude Code runs one claude -p --input-format stream-json process per session. Both used claude-sonnet-4-6.

Measured 2026-09-29 on Linux with jcode v0.89.19-dev (default build, local embeddings not compiled in) and Claude Code 2.1.267. Reproduce with python3 scripts/bench_headless_memory.py.

Time to first frame

Measured on this Linux machine across 10 interactive PTY launches.

Time to first input

(time until typed probe text appears on the rendered screen; Antigravity uses its internal input-ready log marker because the sign-in screen suppresses probe echo.)