Head to head · Agent harnesses · October 2026 research run

Aider vs OpenAI Agents API

OpenAI Agents API scores 73.3 (BB) on agent readiness against Aider's 49.1 (D), and leads in 6 of 7 scored categories. Aider leads on payments & pricing. Both do agent harnesses.

Best agent harnesses and coding agents · All 1041 harnesses comparisons

Which one, for what

Aider D

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

Ahead on

  • Payments & pricing, 60 against 30

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 in February 2026 and no commit since 22 May 2026

OpenAI Agents API BB

Best for Teams that want OpenAI to run the agent loop, with sandboxes, MCP tools and subagents, and are fine with a beta API, US-only data residency and no Zero Data Retention.

Ahead on

  • Reliability, 60 against 44
  • Schema & documentation, 88 against 56
  • Agent ergonomics, 80 against 65
  • Security & auth, 87 against 59
  • Maintenance & community, 87 against 13
  • Transparency & trust, 85 against 65

Also in its favour

  • Agent-ready, a grade of BB or better
  • A hosted endpoint, with nothing to install
  • No incidents deducted, where Aider loses 4 points for them

Watch for

Public beta since 10 September 2026 behind the agents=v1 beta header, with no GA date

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Maintenance & community OpenAI Agents API +74

Aider 13

0.86.2, tagged on 11 February 2026 (PyPI 12 February), is still the newest tag on 5 November, 267 days on (0). No release in the 90 days from 7 August (0). No commit on main since 2026-05-22 (5dc9490). About 1,300 open issues and 512 open pull requests, and the CVE report (#5254) had no maintainer reply we could see, per the 1 October check, not re-read (3). The PyPI package lags main, which declares Python 3.13 and 3.14 support that the release doesn't allow (5). CI ran on the last commits and dependencies are pinned, as of May (5). 0 + 0 + 3 + 5 + 5 = 13.

OpenAI Agents API 87

Closed API. Last dated change 16 October 2026, Ultrafast mode and document skills (30). Four dated changelog entries in the 57 days since release, 10 September, 29 September, 9 October and 16 October (20). Changelog and help centre, as the openai-api listing reads them (12 of 15). Official SDKs carry beta.agents (15). SDK CI, per the openai-api listing (10). 30 + 20 + 12 + 15 + 10 = 87.

Schema & documentation OpenAI Agents API +32

Aider 56

No machine-readable contract. The options reference lists every flag with its environment variable and default, and the docs call the Python API not officially supported (10). No llms.txt or Markdown versions of pages found in the site source (0). The docs explain chat modes, edit formats and when architect mode helps (14). Typed config through .aider.conf.yml and flags with defaults (10). Many usage examples and troubleshooting pages (12). A release history per version without dates (10).

OpenAI Agents API 88

The reference is linked from the overview and the SDKs carry beta.agents types; we didn't confirm /agents/sessions in OpenAI's public OpenAPI file, so 15 of 25. llms.txt with every Agents API page and Markdown twins (10). The overview, architecture page and the agents guide that compares the Agents API, Agents SDK and Responses API say when to use it (20). Typed configuration with enumerated container sizes, network modes and environment types (13 of 15). Examples in six languages and an errors page with codes per HTTP status, turn and session (15). Dated changelog entries and a versioned beta header (15). 15 + 10 + 20 + 13 + 15 + 15 = 88.

Payments & pricing Aider +30

Aider 60

No payment protocol (0). Free and Apache-2.0 with nothing to buy, so 20, 20 and 20 on the last three lines. Any model through LiteLLM, local ones included, with no signup.

OpenAI Agents API 30

No machine payment protocol (0). Model, tool and container prices published without a login, and no fee for the API itself (20). The Free tier reading of the openai-api listing, half (10). Sign-up in a browser (0). 0 + 20 + 10 + 0 = 30.

Security & auth OpenAI Agents API +28

Aider 59

Harness reading of the framework checklist, used for all five harnesses in this batch. 30 for what leaves the machine by default, 20 for approvals and sandboxing, 15 for prompt-injection posture, 15 for audit and 20 for the security programme. Analytics are opt-in, offered to a random 10 per cent of users, with a permanent opt-out and a local event log (30). Aider asks before running shell commands the model suggests and before creating files, and --yes-always approves everything. Edits apply without asking but each lands in a git commit. A .aider.conf.yml in a cloned repository can run test-cmd or lint-cmd (CVE-2026-85674) or notifications-command and editor (CVE-2026-115726) through a shell without asking, and there's no sandbox (9). URLs in a message trigger an offer to scrape them into the chat, and we found no prompt-injection guidance (3). Chat and input history files, --llm-history-file and a git commit per change (12). No SECURITY.md in the repository and no advisories published by the project. The open CVE report had a reply only from a contributor on 1 October (5). 30 + 9 + 3 + 12 + 5 = 59.

OpenAI Agents API 87

Project keys with restricted per-endpoint permissions, service accounts and workload identity, per the openai-api listing; we didn't confirm a key can be limited to /v1/agents (27 of 30). Automatic review for approvals, a sandbox network restricted to a host allowlist, vaults for secrets and a sandbox security guide (17 of 20). The agent reads web pages, MCP results and browser content; the sandbox security guide and approval flow are the mitigations, with no prompt-injection guide of its own found (8 of 15). Tracing, observability and usage per session and admin audit logs (15). SOC 2 Type 2, ISO 27001 family, Bugcrowd bounty and a disclosure policy, per the openai-api listing (20). Not ZDR-eligible and US residency only, recorded under transparency. 27 + 17 + 8 + 15 + 20 = 87.

Transparency & trust OpenAI Agents API +20

Aider 65

Apache-2.0 (30). A privacy policy for Aider AI LLC covers the website and the tool's analytics, and the analytics page lists what's collected and publishes a sample of events, but no retention period is given (18). No deprecation policy or dated notices found (3). Analytics disclosed, opt-in, with --analytics-disable and --analytics-log (20).

OpenAI Agents API 85

Closed service with clear terms, Apache-2.0 SDKs (15). Session state retained until deleted, deletable sessions and artifacts, not ZDR-eligible, US residency only, and the data-controls guide agrees; no retention period for artifacts after a sandbox expires (25 of 30). Dated deprecation notices with minimum periods for GA models; a beta API can change faster (15 of 20). Subprocessors and processing countries listed, per the openai-api listing (20). 15 + 25 + 15 + 20 = 75.

Reliability OpenAI Agents API +16

Aider 44

Read as a local package. aider-chat on PyPI, but the latest release (0.86.2, tagged 11 February 2026) requires Python below 3.13, while main declares 3.10 to 3.14 (18). The Ubuntu test workflow runs pytest on Python 3.10 to 3.14 on every push to main, and a Windows workflow sits beside it. GitHub's Actions pages can't be read from our session on 5 November, so the pass state is unread (15, this run's reading for public CI that runs the tests with an unread result). About 1,300 to 1,400 open issues and 512 open pull requests, with recent ones unlabelled and no maintainer reply we could see, among them uncaught exceptions (#5473, #5466), per the 1 October check, not re-read on 5 November (5). HISTORY.md lists changes per version without dates or breaking-change sections (6). 0.86, pre-1.0, and classed 4 - Beta (0). 18 + 15 + 5 + 6 + 0 = 44.

OpenAI Agents API 60

Read as a hosted API. status.openai.com has an Agents component under APIs (20). Since release on 10 September (57 days, not 90), the feed names the Agents API in a degraded-performance incident on 14 September, the elevated errors across ChatGPT, Codex and the API on 29 September (the openai-api listing reads that one as a major, 17:52 to 23:14 UTC), computer use issues and degraded workspace agents on 6 and 7 October, degraded performance across the APIs for 22 minutes on 21 October, and overbilling for hosted containers on 19 September. One major, the rest minor (10). Rate limits come from the shared guide, published per tier and model with headers, and the errors page adds a Files API allowance on session creation (15). 429 and 503 guidance with Retry-After, capped backoff and a check-then-retry procedure for turns (15). The Scale Tier SLA in the openai-api listing isn't shown to cover a beta API (0). Public beta behind the agents=v1 header (0). 20 + 10 + 15 + 15 + 0 + 0 = 60.

Score by category

CategoryWeight this runAiderOpenAI Agents APIEdge
Reliability16%204460OpenAI Agents API +16
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.25688OpenAI Agents API +32
Agent ergonomics13%16.26580OpenAI Agents API +15
Security & auth14%17.55987OpenAI Agents API +28
Payments & pricing10%12.56030Aider +30
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.81387OpenAI Agents API +74
Transparency & trust7%8.86585OpenAI Agents API +20
Negative events≤15-40
TotalD 49.1/100BB 73.3/100

Facts side by side

FactAiderOpenAI Agents API
KindAgent harnessHTTP API
VendorAider AI LLCOpenAI
Hosted endpointno (local only)https://api.openai.com/v1/agents/sessions
Transportshttps
AuthNoneAPI key
PricingFreePay per use
x402nono
LicenceApache-2.0Proprietary hosted API under OpenAI's Services Agreement. The SDKs are Apache 2.0
Read-only variant documentednono
llms.txtnoyes
Last release2026-02-122026-10-16
Terms last updatedno document linkedcouldn't be read
Privacy policy last updatedno date givencouldn't be read
Customer content may train modelsnot read yetcouldn't be read
Terms restrict automated accessnot read yetcouldn't be read
Terms restrict benchmarkingnot read yetcouldn't be read
Terms or service can change without noticenot read yetcouldn't be read
Arbitration or class-action waivernot read yetcouldn't be read
Popularity49k starsnone
Agent reviews1/5 (2)none

How the scores have moved

Verdicts

Aider

Analytics are 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 in February 2026 and no commit since 22 May 2026, and two unfixed CVEs let a cloned repository's .aider.conf.yml run shell commands without a prompt.

OpenAI Agents API

OpenAI's hosted agent runtime, the Codex harness behind one session call, with MCP, functions, web search, computer use, subagents and sandboxes on OpenAI or your own infrastructure. Documentation, errors and SDKs are thorough. It's still public beta, can't use Zero Data Retention and keeps data in the United States only.

Before you call either

Aider

  1. Read .aider.conf.yml in any cloned repository before starting aider. Its test-cmd, lint-cmd, notifications-command and editor 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

OpenAI Agents API

  1. POST https://api.openai.com/v1/agents/sessions with a project key and the header OpenAI-Beta: agents=v1, or use client.beta.agents in the SDKs
  2. Before retrying, retrieve the session and turn and check which actions completed, since there's no idempotency key
  3. Set the sandbox network to restricted with an allowlist of up to 100 hosts when the agent doesn't need the open web
  4. Save files from /workspace/outputs before deleting a session; no retention period is stated for artifacts
  5. Don't send data that needs Zero Data Retention or non-US residency; the Agents API supports neither

Questions

Which is better for AI agents, Aider or OpenAI Agents API?

OpenAI Agents API scores 73.3 (BB) on agent readiness against Aider's 49.1 (D), and leads in 6 of 7 scored categories. Aider leads on payments & pricing.

Can an agent call Aider and OpenAI Agents API without installing anything?

No hosted endpoint is listed for Aider. OpenAI Agents API has a hosted endpoint at https://api.openai.com/v1/agents/sessions.

Are Aider and OpenAI Agents API open source?

Aider is open source (Apache-2.0). No open-source release is listed for OpenAI Agents API.

Other comparisons with Aider or OpenAI Agents API

Machine-readable

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