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Side-by-side: what they do, what they cost, what Kai actually thinks. Pass up to 4 tools via ?tools=claude,chatgpt,gemini.
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Symphony
A
Gemini
A
Devin
A
OpenRouter
S
TaglineOpenAI's open-source daemon that turns your Linear board into an always-on coding agent factory — tickets go in, pull requests come out.Google's answer. Best integrated with Workspace + free for a lot.Cognition Labs' autonomous coding engineer.One API, every model. Pay-as-you-go, no subscriptions.
CategoryAgentsChatbotsAgentsDev Platform
PricingFree (open-source)Free + $20/mo Advanced (bundled with 2TB Drive)$500/moPay per token — model-dependent
Best forEngineering teams already using Linear + OpenAI Codex who want to stop babysitting agent sessions and instead let the issue tracker drive autonomous coding at scale.Anyone already on Google, research tasks, summarizing long documents.Engineering teams offloading tickets. Ops/platform work.Developers experimenting across models. Apps that want fallback logic.
Strengths
  • Fully autonomous ticket-to-PR pipeline: every open Linear issue gets its own isolated Codex agent without manual supervision
  • Fault-tolerant Elixir/OTP architecture automatically restarts crashed agents and manages hundreds of concurrent runs
  • WORKFLOW.md keeps all orchestration policy version-controlled inside the repo, so agent behavior is reproducible and reviewable like code
  • Proven internal results: OpenAI reported a 500% increase in landed PRs on some teams within three weeks
  • Open spec encourages community re-implementations in any language, not just Elixir
  • Native Google Workspace integration
  • Very long context (1M+)
  • Deep Research feature
  • Free tier is generous
  • Works like an engineer — takes Slack tasks, opens PRs
  • Handles multi-hour engineering work
  • Reports back with what it did
  • 300+ models from one endpoint
  • Automatic fallbacks between providers
  • No subscription — just pay what you use
Weaknesses
  • Currently only supports Linear as an issue tracker — GitHub Issues and Jira integrations are not yet official
  • Only OpenAI Codex is officially supported as the agent runtime; other model integrations are community-contributed and incomplete
  • Self-hosted, Elixir-dependent engineering preview with no built-in sandboxing — not suitable for untrusted or production environments out of the box
  • Writing quality trails Claude
  • Over-refusals on edge content
  • UI is cluttered
  • Expensive
  • Best for well-scoped tasks
  • Not for solo hobbyists
  • Slight markup over direct API
  • Some provider features not exposed
Kai's verdictSymphony is the most architecturally serious 'issue tracker as control plane' approach yet — 15K GitHub stars in weeks confirms the idea resonates — but it's still a rough, self-hosted engineering preview that demands Elixir chops and a Linear-only workflow. (Verdict pending Phi's full review.)A-tier. The Deep Research feature is genuinely useful. Don't sleep on it if you're already paying Google.A-tier for the right use case. Not for solo devs. If you manage engineers, try one license.S-tier for model-shopping. I use this for every prototype before committing.
LinkOpen →Open →Open →Open →