# Letta vs Orca

> Letta scores 59.7 (C) to Orca's 57.4 (C) for agent harnesses. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/letta-vs-orca
- Markdown: https://www.anchorterminal.com/compare/letta-vs-orca.md (~4,700 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 Orca's 57.4 (C), and leads in 4 of 7 scored categories. Orca leads on security & auth. 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
- Orca: grade C, 57.4/100, rank #791 of 1486. Markdown https://www.anchorterminal.com/tools/orca.md · JSON https://www.anchorterminal.com/api/v1/tools/orca.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:
- Schema & documentation, 70 against 65
- Payments & pricing, 60 against 40
- 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

### Orca (C)

Good for: Developers who want an orchestrator agent to split work across parallel coding agents, on desktop or mobile.

Ahead on:
- Security & auth, 43 against 35

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

Watch for: Anonymous usage data collected by default, with an opt-out


## Why the edge

### Payments & pricing: Letta +20

- Letta (60): No x402, MPP or L402 (0 of 40). Per-unit API prices are public, $0.10 per active agent a month and $0.00015 a second of tool execution, plus plan prices (20). A $0 plan with bring-your-own keys; no card is mentioned (20). The CLI runs locally without signing in (20). Total 60.
- Orca (40): Scored on the cloud option. No protocol (0). The cloud price wasn't found on the pages read (0). The desktop app is free and MIT with no card (20). The local app needs no sign-up that we found (20). 0 + 0 + 20 + 20 = 40.

### 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.
- Orca (75): Tags to v1.4.251 and commits on 6 November 2026 (30). Many 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 builds (15). Extensive CI (10). 30 + 20 + 0 + 15 + 10 = 75.

### Security & auth: Orca +8

- 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.
- Orca (43): Harness reading. Anonymous usage data with an opt-out, per the README's link to its telemetry docs (15 of 30). Worktrees per agent and a sandboxed Linux build (12 of 20). No prompt-injection guidance (5). No audit log (5). A dependency-security workflow (6 of 20). 15 + 12 + 5 + 5 + 6 = 43.

### Schema & documentation: Letta +5

- 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.
- Orca (65): Harness reading. A docs site with CLI orchestration and native chat pages (65).

## Score by category

| Category | Weight | Letta | Orca | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 58 | 58 | even |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 70 | 65 | Letta +5 |
| Agent ergonomics | 13% (16.2 this run) | 67 | 70 | Orca +3 |
| Security & auth | 14% (17.5 this run) | 35 | 43 | Orca +8 |
| Payments & pricing | 10% (12.5 this run) | 60 | 40 | Letta +20 |
| 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 | 54 | Letta +1 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **59.7 · C** | **57.4 · C** | |

## Facts side by side

| Fact | Letta | Orca |
| --- | --- | --- |
| Kind | Agent harness | Agent harness |
| Vendor | Letta | Lovecast 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.

**Orca.** An open-source orchestrator for coding agents with worker agents in their own worktrees, chat and terminal views, a browser and a CLI, on desktop and mobile, with heavy test automation. It collects anonymous usage data by default, and the cloud option's pricing wasn't found.

## 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

### Orca

1. See the telemetry docs on onorca.dev to opt out of anonymous usage data
2. Use the orchestration CLI to hand a large task to one agent that starts workers

## Questions

### Which is better for AI agents, Letta or Orca?

Letta scores 59.7 (C) on agent readiness against Orca's 57.4 (C), and leads in 4 of 7 scored categories. Orca leads on security & auth.

### Are Letta and Orca open source?

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


## For agents

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

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Query this catalogue directly over MCP: https://www.anchorterminal.com/mcp (Streamable HTTP, no key). How: https://www.anchorterminal.com/agents/#mcp