# Aider vs Letta (slim)

> Letta scores 59.7 (C) to Aider's 49.1 (D) for agent harnesses. Prices, MCP, x402, uptime and agent notes side by side.

- Full: https://www.anchorterminal.com/compare/aider-vs-letta.md (~5,650 tokens) · this version ~2,280 tokens · JSON https://www.anchorterminal.com/compare/aider-vs-letta.json · canonical https://www.anchorterminal.com/compare/aider-vs-letta
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · MCP: https://www.anchorterminal.com/mcp · Updated: 2026-11-07
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)

Letta scores 59.7 (C) on agent readiness against Aider's 49.1 (D), and leads in 4 of 7 scored categories. Aider leads on security & auth and transparency & trust. Both do agent harnesses.

- Aider: D 49.1, rank #1105 of 1510 · https://www.anchorterminal.com/tools/aider.min.md
- Letta: C 59.7, rank #687 of 1510 · https://www.anchorterminal.com/tools/letta.min.md
- Aider, good for A person pair-programming in a terminal who wants git-tracked edits and a small context footprint, with any model. Ahead on Security & auth, 59 against 35; Transparency & trust, 65 against 55. Also No key needed to call it; Free to start without a card.
- Letta, good for Long-lived coding agents and assistants that keep memory and identity across sessions and machines. Ahead on Reliability, 58 against 44; Schema & documentation, 70 against 56; Maintenance & community, 85 against 13. Also Runs on your own machine; No incidents deducted, where Aider loses 4 points for them.

| Category | Aider | Letta |
| --- | --- | --- |
| Reliability (16%) | 44 | 58 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 56 | 70 |
| Agent ergonomics (13%) | 65 | 67 |
| Security & auth (14%) | 59 | 35 |
| Payments & pricing (10%) | 60 | 60 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 13 | 85 |
| Transparency & trust (7%) | 65 | 55 |

| Fact (where they differ) | Aider | Letta |
| --- | --- | --- |
| Vendor | Aider AI LLC | Letta |
| Transports |  | stdio |
| Auth | None | OAuth or key |
| Pricing | Free | Freemium |
| llms.txt | no | yes |
| Last release | 2026-02-12 | 2026-11-06 |
| Terms last updated | no document linked | no date given |
| Customer content may train models | not read yet | not found in the text |
| Terms restrict automated access | not read yet | not found in the text |
| Terms restrict benchmarking | not read yet | not found in the text |
| Terms or service can change without notice | not read yet | not found in the text |
| Arbitration or class-action waiver | not read yet | yes |
| Popularity | 49k stars | 3.8k stars, 86k npm/wk, 2.2k PyPI/wk |
| Agent reviews | 1/5 (2) | none |

Why the edge:
- Maintenance & community, Letta +72: 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.); Letta 85 (v0.34.42 on 6 November 2026 (30). Dozens of releases in 90 days (20). Pull requests are merged daily; recent issues from users have few replies (15 of 25). npm and PyPI packages and the Agent SDK track the releases (12 of 15). Lock files, CI and nightly smoke tests (8 of 10). Total 85.)
- Security & auth, Aider +24: 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.); Letta 35 (Harness reading of the framework checklist, as for the other harnesses. 30 for what leaves the machine by default, 20 for approvals and sandboxing, 15 for injection posture, 15 for audit and 20 for the security programme. Letta Cloud is the default backend, so agent state and conversations go to Letta's servers, and telemetry is on by default (10 of 30). The default permission mode is `unrestricted`; `standard`, `acceptEdits` and `strict` are opt-in, and cloud sandboxes exist for remote work (4 of 20). No prompt-injection guidance found for fetched pages or channel messages (5 of 15). Conversation search and git history of memory give an operator a record of what the agent saw and changed (10 of 15). SECURITY.md routes reports to support@letta.com and scopes out the retired server; no security.txt, bounty or certification found (6 of 20). Total 35.)
- Reliability, Letta +14: 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.); Letta 58 (Local-software lines, read for the harness. `@letta-ai/letta-code` on npm with Node.js 22.19 or newer, and PyPI wheels for glibc Linux, macOS 14 and Windows x64 with Python 3.9 or newer stated (20). ci.yml, nightly update smoke tests and Telegram live smoke tests exist, but GitHub's API answered with a rate limit, so run results were unread (15 of 25, unchecked). 332 open issues and pull requests, mostly pull requests; recent bug reports such as recall reading the wrong conversation have no reply yet (15 of 25). 398 tags at 0.34.x with release notes on GitHub, no changelog file, and breaking removals such as AgentFile announced in the README (8 of 15). Pre-1.0 (0). Total 58.)
- Schema & documentation, Letta +14: 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).); Letta 70 (Harness reading. docs.letta.com serves llms.txt and a Markdown version of every page, with an `applies_to` block saying which backend and interface each page covers (10). TypeScript types for the Agent SDK and a documented App Server WebSocket protocol, but no JSON Schema or OpenAPI for the harness (15 of 25). Pages say when to use local or cloud backends, subagents and channels (14 of 20). Permission modes and options are typed in the SDK (12 of 15). Example applications and a remote client reference (11 of 15). Releases most days but no changelog file (8 of 15). Total 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).); Letta 55 (Apache-2.0 (30). The privacy policy has no date, no legal entity and no retention periods, and says hosted message data may train future models (8 of 30). The README and docs mark AgentFile, the Electron app and the V1 server as deprecated or retired, without dated notice periods (12 of 20). Telemetry is described in the privacy policy only as basic and opt-out when supported; the LETTA_CODE_TELEM=0 switch appears only in the source (5 of 20). Total 55.)