Open Source Project #185: Orca — YC-Backed Agent Development Environment for Running a Fleet of Parallel AI Coding Agents

Introduction

"One agent isn't enough. You need five agents attempting the same problem simultaneously, then pick the best one."

This is article #185 in the "One Open Source Project a Day" series. Today's project is Orca — stablyai's (Y Combinator-backed) open-source Agent Development Environment, built for what they call "100x builders."

If Claude Code is one AI coding assistant, Orca is the command center for an entire agent fleet. Run Claude Code, Codex, OpenCode, Grok, and others in parallel from a single interface, each agent working in its own isolated git worktree, while you watch all progress from a unified view, compare diffs, annotate results, and merge the winner — all using your own API subscriptions, with no extra fees to Orca.

36,200 Stars. MIT license. Electron desktop app with iOS and Android clients.

What You'll Learn

• Why Orca sits above individual agent tools: fleet management vs. solo work
• Parallel worktrees: fan one task to multiple agents, compare and merge the best
• Design Mode: click browser elements to inject screenshots and HTML into agent context
• SSH worktrees: run agents on remote machines, control them locally
• Mobile client: monitor and control running agents from your phone
• Inline diff annotation, file drag-and-drop, GitHub and Linear integration

Prerequisites

• Experience with Claude Code, Codex, or a similar AI coding agent
• Basic understanding of git worktrees (or willingness to learn)
• Comfortable in a terminal

The Problem: Single-Agent Workflows Hit a Ceiling

Running one AI coding agent on complex tasks surfaces a few friction points:

• Inconsistent quality: the same prompt produces different quality output across runs
• Linear throughput: wait for one task to finish before starting the next
• Context switching overhead: jumping between GitHub, Linear, terminal, and editor constantly
• No remote visibility: agent is running, you're away, no way to check progress
• UI tasks are hard to describe: "change the button style" is easy to say, hard to convey accurately in text

Orca packages these problems together. The positioning: manage multiple agents the way an engineering lead manages a team.

Core Features

Parallel Worktrees: The Core Capability

This is what separates Orca from everything else in the category.

Workflow:

1. You have a task — implement a feature, fix a bug
2. Fan it out to three agents (Claude Code, Codex, OpenCode) simultaneously
3. Each runs in an isolated git worktree, no interference between them
4. Review all three diffs in Orca, pick the strongest implementation, merge it

main branch
    ├── worktree-1: Claude Code's implementation
    ├── worktree-2: Codex's implementation
    └── worktree-3: OpenCode's implementation
 
Compare three diffs, merge the best

What this buys you:

• Better quality: three shots instead of one, pick the best
• Less wall time: parallel runs mean total time equals the slowest single agent, not the sum
• Real comparison data: test different agents on the same actual task to see where each performs well

Design Mode: The UI Iteration Shortcut

Describing UI changes in text is one of the persistent friction points in AI-assisted frontend work — "make the button more prominent" is easy to say, hard for an agent to interpret correctly.

Orca's Design Mode removes that friction:

1. Open the live preview in Orca's built-in browser
2. Click any UI element
3. Orca captures automatically:
   • Screenshot of the element and its surroundings
   • The element's HTML structure
   • Relevant CSS styles
4. That context goes directly into the active agent's prompt

No manual screenshotting. No copying HTML. No pasting into a chat box. The agent gets actual visual and code context.

Mobile Remote Monitoring

Your agent is running. You're in a meeting or away from your desk. Orca's iOS and Android clients let you:

• Receive real-time agent status notifications
• View live terminal output remotely
• Send new instructions or interrupt a running agent
• No VPN required — direct connection through Orca's protocol

Agent running on MacBook
    ↓
Orca mobile client (iPhone/Android)
    ↓
Notification: "Worktree-2 complete, review requested"

SSH Worktrees: Remote Agent Execution

Your local machine isn't always the right place to run agents — tasks might need more compute, or you want persistent cloud execution. SSH Worktrees let you:

• Connect to any remote Linux or Mac server
• Create worktrees and run agents on the remote machine
• Manage both local and remote agents from the same Orca UI
• Auto-reconnect after network drops (no manual reconfiguration)
• Port forwarding so remote service previews appear on local ports

Inline Diff Annotation

Agent submits a diff. You're reviewing it in Orca and spot something wrong on line 47:

• Write the comment directly on that diff line
• Click "send back to agent"
• Agent receives your annotation and revises

No switching to another tool to write review comments. No describing "that thing near line 47 in the function." Point to the exact line, send it back.

File and Image Drag-and-Drop

Drag files, screenshots, or design mockups into Orca — the content injects into the active agent's prompt context. Drop a Figma export and say "implement this design" without any copying.

WebGL Terminals

Orca's terminals use WebGL rendering rather than DOM-based terminal emulation:

• Infinite splits — one panel per agent, expand horizontally
• Persistent scrollback that survives close and reopen
• Low-latency rendering for long-running agents

GitHub and Linear Integration

From inside Orca:

• Browse GitHub PRs, create agent tasks directly from PRs
• View Linear boards, assign issues to agents by dragging
• Create PRs directly after agents complete their work

Supported Agents

Orca works with any CLI agent. No vendor lock-in:

Claude Code, OpenAI Codex, Grok, Cursor, GitHub Copilot, OpenCode, Amp, Cline, Goose, Devin, Qwen Code, Kimi, Mistral Vibe, Kilocode, Rovo Dev, MiMo Code, and anything that outputs to a terminal.

Key point: your own API keys or subscriptions. Orca adds no per-token charges.

Orca CLI

Beyond the GUI, Orca ships a CLI for scripting workflows:

# Create a new worktree
orca worktree create --name feature-auth --agent claude-code
 
# Screenshot a browser element (script version of Design Mode)
orca snapshot --selector ".login-button"
 
# Simulate a click (Computer Use scenarios)
orca click --selector "#submit"
 
# Fill a form field
orca fill --selector "input[name=email]" --value "test@example.com"

Installation

# macOS (Homebrew)
brew install --cask stablyai/orca/orca
 
# Arch Linux
yay -S stably-orca-bin
 
# Direct download: onorca.dev/download

Mobile:

• iOS: App Store or TestFlight
• Android: APK (v0.0.36+)

Orca vs. Omnigent

Issue #180 covered Omnigent. They're the two most-compared tools in this space:

Decision logic:

• Individual developer wants better local AI coding UX → Orca
• Team needs centralized agent management with policy and cost controls → Omnigent

Project Links

• GitHub: stablyai/orca
• Website: onorca.dev
• Twitter/X: @orca_build
• Backed by: Y Combinator

Summary

Orca's core bet: AI coding agents are shifting from "single-threaded assistants" to "parallelizable engineering resources." One person managing a fleet of agents, running multiple implementation approaches simultaneously, comparing diffs to find the best — this workflow looks increasingly like how a small engineering team operates.

Parallel worktrees are what make it practical. Git worktrees provide the isolation; Orca's UI keeps the cognitive load of managing multiple parallel tasks within reach. Design Mode removes the description friction in UI iteration. The mobile client handles the "agent running, developer away" problem.

These aren't nice-to-haves. Each addresses a specific friction point that surfaces in real AI-driven development work.

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