Amp vs Letta

Amp 23

Local-package reading, as for the other closed-source harnesses. An install script that verifies a SHA-256 checksum, and an @ampcode/cli npm package of prebuilt binaries, for macOS, Linux and Windows through WSL, per the 8 October check (20). The source repository is private, so there is no public CI or test suite (0). There is no public issue tracker, and bug reports go to the vendor from inside the product. The 8 October reading of the status page's incident feed is struck, because ampcodestatus.com's robots.txt now disallows ClaudeBot, Claude-Web and anthropic-ai, so nothing is left to count crash or regression reports against (0). Versions are build stamps such as 0.0.1792627309-g98c009 with no per-version notes, and the introduction says "No backward compatibility", though removals are announced with dates in the Chronicle (3). The version line is 0.0 and we found no statement that the CLI is stable (0).

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.

Amp 35

Harness reading of the published rubric. No payment protocol (0). The pricing page is public. Hobby is free, Megawatt is $20 a month with 45,000 orb minutes, orbs are priced per hour by size from $0.08, and paid credits are charged at provider API prices with no markup outside Enterprise. Gigawatt is $200 a month with $200 of agent usage and 1,000 hours of a1.xxlarge orbs, per the pricing docs (20). Hobby is free when you bring your own model key or subscription and run locally or on your own runner. The pricing page does not say whether sign-up asks for a card, and inference served by Amp is never free (15). A person signs in through a browser to create the access token (0).

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.

Amp 57

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 prompt-injection posture, 15 for audit and 20 for the security programme. Every thread, with messages, code used as context and tool results, is stored on Amp's servers, and there is no local-only or self-hosted mode. Training on user data is off unless a user opts in, provider retention is limited under Minimal Data Retention, and secrets are redacted before they leave the client on a best-effort basis. The terms allow collection of usage data and we found no opt-out for the CLI (14). The tools page says Amp does not ask for approval before running tools, and points to a custom plugin for control. MCP servers defined in a project's settings need approval, amp.mcpPermissions allows or rejects servers and amp.tools.disable removes tools. The CLI has no sandbox. Orbs are separate cloud machines (6). The security reference has a prompt-injection section that describes layered measures, and the tools page warns about untrusted repositories and MCP servers (9). Threads keep prompts, tool calls and results as a record, a data API covers workspace analytics and threads, and authentication audit logs are for Enterprise workspaces (12). A security.txt that expires on 20 November 2026 (still valid on 4 November), a bug bounty with safe harbour, SOC 2 Type II and annual penetration tests per the vendor. On 22 October 2026 the security page posted an update that removes trust in compromised certificate authorities and names the CLI build to install. No CVEs found (16).

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.

Amp 77

Closed source under the Amp licence terms from Amp Frontier Corporation, with the npm packages marked Amp Commercial License. The terms page shows no date (15). The security reference lists 19 providers and what each sees, says deleted threads are removed within 30 days, diagnostic data after 7 days and audit logs kept at least 30 days, and the privacy policy (modified 10 September 2026) agrees, with account data kept while the account is active (24). No deprecation policy. The terms allow any part of the Services to be discontinued without notice, while removals so far were announced with dates, such as the old npm package names on 14 May 2026 for removal on 15 June (8). Amp is local software tied to a hosted service. Providers and US hosting are disclosed in detail, but the usage data the client sends is not itemised and has no documented opt-out (12).

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.

Amp 79

The security page names CLI build 0.0.1792627309-g98c009 in its 22 October 2026 update, and the Chronicle's newest post is Service Accounts on 3 November 2026 (30). The Chronicle has 44 dated posts from 6 August to 3 November, and npm listed 678 CLI versions between 10 July and 8 October per the 8 October check (20). No public tracker. Support is in-product bug reports, a Discord server, email and X. Reply times aren't visible (10). @ampcode/sdk on npm released on 18 September 2026, per the 8 October check, and the SDK docs cover TypeScript and Python (15). No public CI, builds carry no notes, and the installer checks a checksum (4).

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.