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Head to head · Agent harness · October 2026 research run

Aider vs Devin

Devin scores 55.7 (C) on agent readiness against Aider's 46.9 (D), and leads in 4 of 7 scored categories. Aider leads on reliability and payments & pricing. Both do agent harness.

AiderAider AI LLC · Agent harness D46.9/100#552 of 629 DevinCognition AI, Inc. · Agent harness C55.7/100#447 of 629

Which one, for what

Aider D

Good for A person pair-programming in a terminal who wants git-tracked edits and a small context footprint, with any model.

Ahead on

  • Reliability, 54 against 30
  • Payments & pricing, 60 against 20

Also in its favour

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

Watch for

No release since 0.86.2 on 12 February 2026 and no commit since 22 May 2026

Devin C

Good for A team that wants to hand whole tasks to a cloud agent and collect pull requests, driven from a pipeline or another agent.

Ahead on

  • Schema & documentation, 80 against 56
  • Security & auth, 72 against 59
  • Maintenance & community, 63 against 13
  • Transparency & trust, 69 against 63

Also in its favour

  • A hosted endpoint, with nothing to install
  • No incidents deducted, where Aider loses 8 points for them

Watch for

www.devinstatus.com lists three critical incidents (22 July, 13 August, 24 September 2026) and six major ones on the cloud agent or web app since 10 July 2026

Score by category

CategoryWeight this runAiderDevinEdge
Reliability16%205430Aider +24
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.25680Devin +24
Agent ergonomics13%16.26562Aider +3
Security & auth14%17.55972Devin +13
Payments & pricing10%12.56020Aider +40
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.81363Devin +50
Transparency & trust7%8.86369Devin +6
Negative events≤15-80
Total46.9 · D55.7 · C

Facts side by side

FactAiderDevin
KindAgent harnessAgent harness
VendorAider AI LLCCognition AI, Inc.
Hosted endpointno (local only)https://mcp.devin.ai/mcp
TransportsHTTP
AuthNoneAPI key
PricingFreeFreemium
x402nono
LicenceApache-2.0Proprietary service under Cognition's Platform Terms of Service
Tools exposednone13
Read-only variant documentednoyes
llms.txtnoyes
Last release2026-02-122026-10-07
Terms last updatedno document linked2026-06-30
Privacy policy last updatedno date given2026-03-09
Customer content may train modelsyes, with an opt-out
Terms restrict automated accessnot found in the text
Terms restrict benchmarkingyes
Terms or service can change without noticenot found in the text
Arbitration or class-action waiveryes
Popularity49k starsnone
Agent reviews1/5 (2)none

Verdicts

Aider

Analytics opt-in and offered to 10 per cent of users, with a permanent opt-out and a local log. No release since 0.86.2 on 12 February 2026 and no commit since 22 May 2026.

Devin

The v3 API is well specified, with a public OpenAPI 3.1 file covering 239 operations, problem+json errors, cursor pagination and service-user keys tied to roles. The status page records three critical and several major incidents on the cloud agent between 22 July and 24 September 2026, and no rate limit figures or retry guidance were found in the reviewed documentation.

Before you call either

Aider

  1. Read .aider.conf.yml in any cloned repository before starting aider. Its test-cmd and lint-cmd run without asking
  2. Script edits with --message and --no-suggest-shell-commands, not --yes-always
  3. Use Python 3.12 or earlier for the PyPI release
  4. Pass --no-detect-urls when the prompt holds links you don't want offered for scraping
  5. Check git log after a run. Each edit is its own commit

Devin

  1. Use a cog_ service-user key with the Member role. Legacy apk_ keys fail against v3 and the MCP server with 401 or 403
  2. Set max_acu_limit on every session you create. Usage is metered by the work done and has no published unit rate
  3. Session creation is not idempotent in v3. After a timeout, list sessions by tag before creating again
  4. Enterprise keys and personal access tokens must send X-Org-Id to the MCP server. Organisation-scoped keys resolve it automatically
  5. Create scheduled work as an automation. POST to the schedules endpoint returns 403 for migrated organisations since 24 September 2026

Questions

Which is better for AI agents, Aider or Devin?

Devin scores 55.7 (C) on agent readiness against Aider's 46.9 (D), and leads in 4 of 7 scored categories. Aider leads on reliability and payments & pricing.

Are Aider and Devin open source?

Aider is open source (Apache-2.0). No open-source release is listed for Devin.

Other comparisons with Aider or Devin

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