# Letta vs T3 Code

> Letta scores 59.7 (C) to T3 Code's 51.9 (D) for agent harnesses. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/letta-vs-t3-code
- Markdown: https://www.anchorterminal.com/compare/letta-vs-t3-code.md (~4,850 tokens)
- Site index for agents: https://www.anchorterminal.com/llms.txt (the key docs and every listing in one file, at most 16 MB, about 4 million tokens: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
- DNS: dig +short TXT <slug>.grade.anchorterminal.com (the grade as a DNS TXT record, for a sandbox with no HTTP where names still resolve; also top., best.<category>. and <a>.vs.<b>. under the zone, and the same under grade.letme.dev)
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)
- Updated: 2026-11-07

Letta scores 59.7 (C) on agent readiness against T3 Code's 51.9 (D), and leads in 5 of 7 scored categories. Both do agent harnesses.

- Letta: grade C, 59.7/100, rank #684 of 1486. Markdown https://www.anchorterminal.com/tools/letta.md · JSON https://www.anchorterminal.com/api/v1/tools/letta.json
- T3 Code: grade D, 51.9/100, rank #1002 of 1486. Markdown https://www.anchorterminal.com/tools/t3-code.md · JSON https://www.anchorterminal.com/api/v1/tools/t3-code.json
- Best agent harnesses and coding agents: https://www.anchorterminal.com/best/agent-harnesses/index.md
- All 1500 harnesses comparisons: https://www.anchorterminal.com/compare/agent-harnesses/index.md
- Best memory layers for AI agents: https://www.anchorterminal.com/best/agent-memory/index.md
- All 353 memory comparisons: https://www.anchorterminal.com/compare/agent-memory/index.md

## Which one, for what

### Letta (C)

Good for: Long-lived coding agents and assistants that keep memory and identity across sessions and machines.

Ahead on:
- Reliability, 58 against 43
- Schema & documentation, 70 against 55
- Agent ergonomics, 67 against 60
- Maintenance & community, 85 against 75

Also in its favour:
- Runs on your own machine

Watch for: The default permission mode is `unrestricted`, the renamed `bypassPermissions`, so tool calls aren't confirmed unless the user picks another mode

### T3 Code (D)

Good for: Developers who want one app, including on their phone, to drive several coding agents they already pay for.

Also in its favour:
- No key needed to call it

Watch for: Usage data on by default, with hashed OpenAI and Claude account identifiers, and relay traces to Axiom


## Why the edge

### Reliability: Letta +15

- 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.
- T3 Code (43): Local software. An install script and desktop and mobile apps from the vendor (20). ci.yml and windows-tests.yml run on the repository; pass state not read (15). GitHub issues and pull requests weren't read (GitHub's pages refuse these sessions), so that line is scored absent (0). Stable tags v0.1.5 to v0.1.7 with many nightlies, no changelog file (8). Version 0.1.7 (0). 20 + 15 + 0 + 8 + 0 = 43.

### Schema & documentation: Letta +15

- 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.
- T3 Code (55): Harness reading. User docs in the repository (managed policy, handoffs, providers, telemetry), AGENTS.md for contributors, a server other clients connect to (55).

### Maintenance & community: Letta +10

- 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.
- T3 Code (75): Commits and nightly tags on 6 November 2026 (30). More than three releases in 90 days (20). GitHub issues and pull requests weren't read (GitHub's pages refuse these sessions), so that line is scored absent (0). Current official apps and install script (15). CI on push (10). 30 + 20 + 0 + 15 + 10 = 75.

### Agent ergonomics: Letta +7

- Letta (67): Harness reading. Toolsets switch with `/model`, skills load per agent, and subagents run in the background (18 of 25). Context is managed through memory blocks, reflection and dreaming (12 of 20). `letta -p --output-format json` for scripted runs and an App Server for programmatic control (12 of 20). Conversations resume by agent and conversation id, and memory is git-tracked so changes can be reverted (15 of 20). Runs with no account on the local backend, with one SDK language, TypeScript (10 of 15). Total 67.
- T3 Code (60): Harness reading. Remote control from phone or browser, portable handoffs between providers and managed policies for teams (60).

## Score by category

| Category | Weight | Letta | T3 Code | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 58 | 43 | Letta +15 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 70 | 55 | Letta +15 |
| Agent ergonomics | 13% (16.2 this run) | 67 | 60 | Letta +7 |
| Security & auth | 14% (17.5 this run) | 35 | 35 | even |
| Payments & pricing | 10% (12.5 this run) | 60 | 60 | even |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 85 | 75 | Letta +10 |
| Transparency & trust | 7% (8.8 this run) | 55 | 51 | Letta +4 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **59.7 · C** | **51.9 · D** | |

## Facts side by side

| Fact | Letta | T3 Code |
| --- | --- | --- |
| Kind | Agent harness | Agent harness |
| Vendor | Letta | T3 Tools Inc. |
| Hosted endpoint | no (local only) | no (local only) |
| Transports | stdio |  |
| Auth | OAuth or key | None |
| Pricing | Freemium | Free |
| x402 | no | no |
| Licence | Apache-2.0 | MIT |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| Last release | 2026-11-06 | 2026-11-06 |
| Terms last updated | no date given | no document linked |
| Privacy policy last updated | no date given | no document linked |
| Customer content may train models | not found in the text | not read yet |
| Terms restrict automated access | not found in the text | not read yet |
| Terms restrict benchmarking | not found in the text | not read yet |
| Terms or service can change without notice | not found in the text | not read yet |
| Arbitration or class-action waiver | yes | not read yet |
| Popularity | 3.8k stars, 86k npm/wk, 2.2k PyPI/wk | none |

## Verdicts

**Letta.** Letta's open-source harness gives agents git-tracked memory blocks, skills, subagents and headless JSON runs, with a $0 plan and public per-agent API prices. It starts in the unrestricted permission mode, defaults to Letta Cloud, sends usage telemetry unless LETTA_CODE_TELEM=0 is set, and the V1 API server the comparisons describe is retired.

**T3 Code.** A fast-moving open-source way to run and steer several coding agents from desktop, browser or phone, using the subscriptions you already have. It's pre-1.0, and it sends usage data by default, including hashed identifiers for your OpenAI and Claude accounts, with the opt-out documented outside the README.

## Before you call either

### Letta

1. Start headless runs with an explicit permission mode such as `standard` or `strict`; the default auto-approves tools
2. Pass `--backend local` for work that must stay on the machine, since Letta Cloud is the default
3. Set LETTA_CODE_TELEM=0 in unattended runs if usage events must not be sent
4. Use `letta -p --output-format json` for scripted runs and parse the JSON, not the terminal output
5. Don't plan on the retired V1 REST server or `.af` AgentFile import; both are gone

### T3 Code

1. Set T3CODE_TELEMETRY_ENABLED=false before starting the server if you don't want usage events sent
2. Install and log in to at least one provider CLI first, such as codex login or claude auth login
3. Use a managed policy to fix settings across a team

## Questions

### Which is better for AI agents, Letta or T3 Code?

Letta scores 59.7 (C) on agent readiness against T3 Code's 51.9 (D), and leads in 5 of 7 scored categories.

### Are Letta and T3 Code open source?

Yes. Letta is open source (Apache-2.0). T3 Code is open source (MIT).


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/letta-vs-t3-code.json, and with the fewest tokens: https://www.anchorterminal.com/compare/letta-vs-t3-code.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "letta", "b": "t3-code"}`. From a terminal: `anchor compare letta t3-code`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/letta.json and https://www.anchorterminal.com/api/v1/tools/t3-code.json

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