Mem0 vs Letta: extracted memory comparison

Side-by-side after 3 weeks of using both in parallel on the same chat corpus.

Setup

I forked my Claude Code session log (about 280 conversations, 6 months) and fed it through both Mem0 and Letta. Both got the same input, same time window. I asked each: "Summarise what you know about me as a developer."

What Mem0 produced

  • Facts. Direct, dry, accurate. "User is building mdfy.app. User prefers Rust + TypeScript. User has shipped 3 Chrome extensions." Mostly nouns and verbs.
  • Extraction quality. Strong. It picked up the cross-AI thesis from the corpus correctly, including the specific phrase "structural moat."
  • Misses. Anything stylistic. It noted "user works in Korean and English" but didn't capture how I work in each. The where-and-when-I-write-Korean nuance was invisible.

What Letta produced

  • Preferences and reflexes. "User typically reaches for the smallest possible scope when refactoring. User stops feature work when QA finds three issues in a row and shifts to a fix pass."
  • Extraction quality. Looser but more interesting. The work-shape observations weren't anywhere in any single message; they're inferred from patterns.
  • Misses. Names of specific tools and products were inconsistent. It flipped between "the editor" and "VS Code" mid-paragraph.

Where they're the same

Both are extracted memory. Both ask the LLM to look at conversation history and produce a profile. The user doesn't author it; the user doesn't directly edit it (though both have "forget that" affordances).

Where mdfy is doing a different thing

mdfy asks: what do you want to remember? The user authors it. The AI reads it. The two questions are complementary, not competing — but they produce different artifacts:

  • Mem0/Letta artifact: a generated profile based on what the AI inferred you cared about.
  • mdfy artifact: a curated hub based on what you decided you wanted to keep.

What I'd love to see

Mem0 + mdfy as siblings: Mem0 produces the inferred profile, you optionally promote any inference to a permanent mdfy doc with one click. The "AI suggested, you author the canonical version" loop.