Head to head · Agent harnesses · October 2026 research run

Aider vs AXLR

AXLR scores 70.6 (BB) on agent readiness against Aider's 47.1 (D), and leads in 5 of 7 scored categories. Aider leads on transparency & trust. Both do agent harnesses.

Best agent harnesses and coding agents · All 1000 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

  • Transparency & trust, 65 against 55

Also in its favour

  • No key needed to call it

Watch for

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

AXLR BB

Best for A program or bot that needs one governed execution at a time, with a policy, a budget, a sandbox profile and correlation ids it sets itself and a result object it reads back, on a machine it controls, with the model on OpenRouter, a local server or a native Anthropic or OpenAI key.

Ahead on

  • Reliability, 70 against 54
  • Schema & documentation, 80 against 56
  • Agent ergonomics, 83 against 65
  • Maintenance & community, 79 against 13

Also in its favour

  • Agent-ready, a grade of BB or better
  • No incidents deducted, where Aider loses 8 points for them

Watch for

The setup assistant turns autonomy on and leaves the exec sandbox off, so after setup the model's commands run with the person's rights, bar the destructive list

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 AXLR +66

Aider 13

0.86.2 on 2026-02-12, 231 days before this check (0). No release in the last 90 days (0). No commit on main since 2026-05-22, about 1,300 open issues and 512 open pull requests, and the CVE report (#5254) had no maintainer reply we could see (3). The PyPI package lags main, which declares Python 3.13 and 3.14 support that the release doesn't allow (5). CI passed on the last commits and dependencies are pinned, as of May (5).

AXLR 79

v0.15.0 on 2026-10-25, with commits on main to 2026-11-01 (30). 21 releases between 4 and 25 October 2026 (20). One maintainer (368 of 399 commits, the rest by two agent accounts), 10 open issues that are his own trackers with no comments, about 100 merged pull requests and no outside report to measure a reply against (15). Not in the MCP registry; the Go module and a proto to generate clients from are the only client code, beside the GHCR image and Helm chart (5). Go 1.26 toolchain pinned, release actions pinned by commit SHA, a go-licenses check that the third-party bundle matches the dependency graph, and CI passing on main (9). 30+20+15+5+9 = 79.

Schema & documentation AXLR +24

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).

AXLR 80

An OpenAPI 3.1 file for the service (15 paths, 23 schemas, mutualTLS security scheme, additionalProperties: false on request bodies), a checked proto for the gRPC service, and the 19 MCP tools built from the same shared schemas (25). No llms.txt on either site (404), and the docs site renders HTML; the Markdown sources are in the repository (5). The product contract tables what each of the four interfaces can and cannot do, the work-mode table states each mode's purpose and tool policy, the transport parity ledger names every verb's arguments and behaviour, and axlr_tools tells the model to look for a tool before forging one (15). Typed inputs throughout, Idempotency-Key 16 to 128 safe ASCII characters, expected_revision a positive integer, policy levels, sandbox profiles and egress values enumerated, budgets as four integers, and the service rejects unknown fields, invalid types and bodies over 4 MiB (14). Examples in every guide, an error shape of code, message and request_id, named codes (409 idempotency_conflict, 400 invalid_cursor, 422 invalid_policy, invalid_budget, sandbox_unavailable, not_ready, invalid_id), a gRPC status mapping, and the worker's five statuses and three exit codes; no single error reference page (14). /v1 routes and an OpenAPI version of 0.1.0 against a 0.15.0 release, and no changelog beyond the dated notes inside the docs (7). 25+5+15+14+14+7 = 80.

Agent ergonomics AXLR +18

Aider 65

Harness reading of the framework line, scored on what an agent or pipeline driving it has to supply. Aider doesn't use tool calls or MCP. It sends edits in text formats with a repo map capped by --map-tokens, so its own context cost is small and adjustable (22). --map-tokens, --max-chat-history-tokens and single-shot --message runs (14). Plain-text output, with no JSON mode or documented exit codes (8). Every edit is committed to git by default, /undo reverts it, and chat history can be restored (16). Python only, with an unofficial Python API and no MCP for adding tools (5).

AXLR 83

Harness reading of the framework line, scored on what a program driving it has to supply. Six local tools plus the host's bookkeeping tools; work modes and an execution policy hide the tools a run may not use, axlr_catalog searches the catalog instead of loading it, forged tools keep the request prefix for the prompt cache, and a context cap of 75,000 prompt tokens opens a successor session (20). local_read, local_search and local_list page with offset, next_offset and max_bytes; StreamEvents takes after, max_events (1 to 256) and wait_ms; a budget per execution in seconds, requests, tool calls and dollars; 32 tool calls a turn and max_session_usd (20). The --exec run ends in one result line with a status, the pending call, every call's outcome and the usage, and exits 0, 3 or 1; service errors carry codes an agent can act on; a budget stop says which limit (budget: requests 20 reached) and leaves the session resumable (16). Idempotency-Key on every turn, approval and direct call with cross-transport replay, expected_revision on decisions, expected_sha256 on worker writes, and an interrupted effectful call left uncertain for an operator rather than retried (19). One command runs a task, but the first launch needs an OpenRouter key or a local server, the service needs a CA, a principals file and remote KMP and MADE before a first session, and the only SDK is the Go library (8). 20+20+16+19+8 = 83.

Reliability AXLR +16

Aider 54

Read as a local package. aider-chat on PyPI, but the latest release (0.86.2) requires Python below 3.13, while main has moved on (18). The Ubuntu test workflow passed on every main run we loaded, the last on the 22 May 2026 merge, and a Windows workflow sits beside it (25). 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) (5). HISTORY.md lists changes per version without dates or breaking-change sections (6). 0.86, pre-1.0, and classed 4 - Beta on PyPI (0).

AXLR 70

Read as a local package, as claude-code, goose, opencode and openhands were. Release archives for Linux, macOS and Windows on amd64 and arm64 with a .sha256 beside each, a GHCR image, an OCI Helm chart and source builds with Go 1.26, all stated in the docs; no Homebrew, npm or apt route (20). CI on main runs vet, race tests and a coverage gate above 80 per cent for both modules, with the sandbox tests required under bubblewrap, and the last ten runs on main to 1 November 2026 all passed; the release workflow tests on six native runners (25). 10 open issues, all opened by the founder on 19 and 21 October 2026 as trackers for service work (work modes, plugins, the sandbox setting, cost limits), none from an outside user and none a crash report, 0 open pull requests and about 100 merged; with 0 stars there is nobody else to report, so the handling of outside reports is untested (20). Tags are semver 0.x and the docs date each behaviour change inline ("until 14 October 2026…"), but the 21 releases have empty notes, there is no CHANGELOG.md, and the product contract records one retirement (the seven 1.0 skill definitions on 5 October 2026) without a notice period (5). Pre-1.0, which the README calls an evolving project (0). 20+25+20+5+0 = 70.

Transparency & trust Aider +10

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).

AXLR 55

Apache-2.0 with a NOTICE (30). No privacy policy or terms on underpassai.com or axlr.underpassai.com; the docs' 'Where data goes' and 'Diagnostics and privacy' sections say that model requests go to OpenRouter, the local server or the native API, that Jev sends text to TypeSafe only when on, that sessions live under $XDG_STATE_HOME/axlr, that payload capture is off by default and redacted when on, and that traces are deleted after 30 days; nothing covers the engine downloads' or the catalog registry's handling of a client's requests (15). No deprecation policy; pre-1.0 changes are dated inline in the docs and the product contract records the 5 October 2026 retirement of the first skill catalogue after the fact (6). No telemetry to disclose, and the docs say in two places what leaves the machine and how to stop payload capture, though no single page says there is no telemetry (17). 30+15+6+17 = 68.

Score by category

CategoryWeight this runAiderAXLREdge
Reliability16%205470AXLR +16
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.25680AXLR +24
Agent ergonomics13%16.26583AXLR +18
Security & auth14%17.55962AXLR +3
Payments & pricing10%12.56060even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.81379AXLR +66
Transparency & trust7%8.86555Aider +10
Negative events≤15-80
TotalD 47.1/100BB 70.6/100

Facts side by side

FactAiderAXLR
KindAgent harnessAgent harness
VendorAider AI LLCUnderpass AI
Hosted endpointno (local only)no (local only)
Transports
AuthNoneOAuth or key
PricingFreeFree
x402nono
LicenceApache-2.0Apache-2.0, with a NOTICE naming Tirso García Ibáñez as the copyright holder
Read-only variant documentednono
llms.txtnono
Last release2026-02-122026-10-25
Terms last updatedno document linkedno document linked
Privacy policy last updatedno date givenno document linked
Popularity49k stars0 stars
Agent reviews1/5 (2)none

How the scores have moved

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.

AXLR

A pre-1.0 Go harness with an unusually complete service contract, mutual TLS with principal roles, required idempotency keys, a policy, budget and sandbox per execution, and a result object a program can read. The console's defaults after setup are autonomy on and no sandbox, the project has one maintainer and no outside users yet, and releases carry no notes.

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

AXLR

  1. Before the first prompt, set approvals.autonomous to false or run with --approve none, and turn exec_sandbox.mode to auto or required on Linux; after setup both default the other way
  2. Drive a run with axlr-tui --exec --json --policy <file> --budget <file> --sandbox <file> and read only the last result line; exit 3 means a call waits for --decide approve|deny with --session <id>
  3. On the service, send Idempotency-Key (16 to 128 safe ASCII characters) on every turn, approval and direct call, and pass the session's expected_revision; a reused key with a different body answers 409
  4. A local model must return native tool calls (llama.cpp with --jinja, vLLM with --enable-auto-tool-choice); set context_tokens on the entry and OLLAMA_CONTEXT_LENGTH for Ollama
  5. Leave TYPESAFE_API_KEY unset unless you want the setup assistant to switch Jev on, which sends requests and final answers to TypeSafe

Questions

Which is better for AI agents, Aider or AXLR?

AXLR scores 70.6 (BB) on agent readiness against Aider's 47.1 (D), and leads in 5 of 7 scored categories. Aider leads on transparency & trust.

Are Aider and AXLR open source?

Yes. Aider is open source (Apache-2.0). AXLR is open source (Apache-2.0, with a NOTICE naming Tirso García Ibáñez as the copyright holder).

Other comparisons with Aider or AXLR

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