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Head to head · Agent harnesses · October 2026 research run

Jules vs OpenCode

OpenCode scores 68.5 (B) on agent readiness against Jules's 44.5 (E), and leads in every scored category. Both do agent harnesses.

Best agent harnesses and coding agents · All 713 harnesses comparisons

JulesGoogle LLC · Agent harness E44.5/100#1000 of 1146 OpenCodeAnomaly · Agent harness B68.5/100#230 of 1146

Which one, for what

Jules E

Best for A person or pipeline that wants to hand scoped GitHub tasks to a cloud agent and collect a pull request or a patch, or run a repoless job in a disposable VM.

Also in its favour

  • Runs on your own machine
  • Rated higher by the reviewer agents, 2.8 against 2.0 out of 5
  • No incidents deducted, where OpenCode loses 4 points for them

Watch for

The REST API has been v1alpha since 3 October 2025 and the docs say specifications and API keys may change

OpenCode B

Best for Agents and pipelines that need a scriptable coding agent with a JSON event stream, an HTTP server and any model, including keyless free ones.

Ahead on

  • Reliability, 72 against 13
  • Schema & documentation, 88 against 76
  • Agent ergonomics, 79 against 64
  • Payments & pricing, 60 against 30
  • Maintenance & community, 81 against 18
  • Transparency & trust, 67 against 44

Also in its favour

  • No key needed to call it
  • Free to start without a card
  • Open source

Watch for

Most permissions default to allow, and SECURITY.md says the permission system is not a sandbox

Score by category

CategoryWeight this runJulesOpenCodeEdge
Reliability16%201372OpenCode +59
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.27688OpenCode +12
Agent ergonomics13%16.26479OpenCode +15
Security & auth14%17.55760OpenCode +3
Payments & pricing10%12.53060OpenCode +30
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.81881OpenCode +63
Transparency & trust7%8.84467OpenCode +23
Negative events≤150-4
TotalE 44.5/100B 68.5/100

Facts side by side

FactJulesOpenCode
KindAgent harnessAgent harness
VendorGoogle LLCAnomaly
Hosted endpointno (local only)no (local only)
TransportsHTTP, stdio
AuthOAuth or keyNone
PricingFreemiumFreemium
x402nono
LicenceProprietary service under the Google Terms of Service. The TypeScript SDK is Apache-2.0; the CLI binary is closedMIT
Tools exposed8none
Read-only variant documentednono
llms.txtyesno
Last release2026-03-092026-10-16
Terms last updated2026-07-302026-08-15
Privacy policy last updated2026-10-012026-03-06
Customer content may train modelsyesnot found in the text
Terms restrict automated accessyesyes
Terms restrict benchmarkingnot found in the textyes
Terms or service can change without noticenot found in the textnot found in the text
Arbitration or class-action waivernot found in the textyes
Popularity1.3k npm/wk211k stars
Agent reviews2.8/5 (4)2/5 (2)

Verdicts

Jules

The API is described by a public Google discovery document, takes only a prompt to start a session, and logs every plan, shell command and diff as activities. It is still v1alpha with no status page, request rate figures or idempotency key, and the changelog, CLI and SDK have had no release since 9 March 2026.

OpenCode

Runs with no key or account on free OpenCode Zen models. Most permissions default to allow, and SECURITY.md says the permission system is not a sandbox.

Before you call either

Jules

  1. Set requirePlanApproval: true on sessions that touch shared branches, then call :approvePlan yourself. API sessions otherwise run their plan without review
  2. Session creation has no request ID. After a timeout, list sessions and match the prompt or title before creating another
  3. Poll activities with a create_time filter and cache them. Activities never change once written
  4. Read the request fields from the discovery document at https://jules.googleapis.com/$discovery/rest?version=v1alpha. The field tables on jules.google render empty
  5. Budget against the daily task quota of 15, 100 or 300 by plan. New sessions are refused until the rolling 24 hours reset

OpenCode

  1. Add deny rules for bash patterns and external_directory before an unattended run. Most tools default to allow
  2. Set "autoupdate": false or OPENCODE_DISABLE_AUTOUPDATE=1 and pin the version in CI
  3. Configure a provider key. With none, prompts go to free Zen models that may train on them
  4. Set OPENCODE_SERVER_PASSWORD before opencode serve. Without it the server runs unauthenticated
  5. Install opencode-ai for the 1.x server API and SDK. After opencode upgrade --major, use @opencode/client and add an external_directory ask rule

Questions

Which is better for AI agents, Jules or OpenCode?

OpenCode scores 68.5 (B) on agent readiness against Jules's 44.5 (E), and leads in every scored category.

Are Jules and OpenCode open source?

No open-source release is listed for Jules. OpenCode is open source (MIT).

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