Mem0 vs Supermemory vs Hjarni: AI Memory Compared (2026)

Mem0 and Supermemory are memory APIs: developers use them to build memory into AI products. Hjarni is a knowledge base with a built-in MCP server: you write notes, and Claude or ChatGPT reads them in every conversation. Building software? Pick Mem0 or Supermemory. Want your own AI to remember your work? Pick Hjarni.

That is the honest version. Most of the Mem0 vs Supermemory debate is a fair fight inside one category, and we get to it below. Hjarni sits in a different category. All three promise the same outcome, an AI that stops starting from zero, and picking the wrong category wastes more time than picking the wrong tool.

One disambiguation first: Mem0 is not Mem. Mem is an AI note app, and we compare it separately in Hjarni vs Mem.

Mem0 vs Supermemory vs Hjarni: side by side

	Mem0	Supermemory	Hjarni
Category	Memory API for builders	Memory API for builders	Knowledge base with MCP
Memory model	Extracted fragments, optional graph	Extracted fragments, fast recall	Markdown notes, folders, tags
Created by	Automatic extraction	Automatic extraction	You write, or your AI writes
Human-readable	Dashboard inspection	Dashboard inspection	Yes, it is a note app
Instructions	Set in your app's code	Set in your app's code	Per folder, per team
MCP support	OpenMemory server, editor plugins	MCP server, Claude Code plugin	Built-in, one hosted URL
Works from any device	Self-host or integrate	Self-host or integrate	Yes, hosted
Free tier	10K memories, capped retrievals	$5 of monthly usage included	Real free tier, full MCP
Paid from	$19/mo	$19/mo	$10/mo

Pricing as listed by each vendor in June 2026.

What Mem0 is

Mem0 is the established name in agent memory. Your application sends it conversations, it extracts facts, deduplicates them, and serves them back through an API. Higher tiers add graph memory. OpenMemory, its open source local MCP server, shares memory across tools on one machine. Its 2026 editor plugins wire memory directly into Claude Code, Cursor, and Codex.

Pick Mem0 when you are shipping an agent product and want proven, documented memory infrastructure with a large community behind it.

The trade-offs: extraction is automatic, so the system decides what mattered. Memories are retrieval fragments, not documents. And the paid ladder climbs fast: Starter at $19, Growth at $79, Pro at $249 per month.

What Supermemory is

Supermemory is the challenger, and it competes on speed. One API handles ingestion, extraction, contradiction handling, and recall. Its pricing page claims sub-300ms p50 latency for search. Pricing is usage based: the free tier includes $5 of monthly usage, and the $19 Pro plan includes about $20, as listed in June 2026.

Pick Supermemory when recall latency is in your product's critical path, or when you want to prototype on the free usage credit before paying.

The trade-offs: it has a shorter public track record than Mem0, and usage based pricing takes some math to predict. Like Mem0, it asks you to trust automatic extraction.

What Hjarni is

Hjarni is a note app your AI can read. You write Markdown notes in folders with tags. Claude and ChatGPT connect through the built-in MCP server with one URL, then search, read, and create notes in every conversation that follows. Nothing is extracted behind your back: the memory is the notes, and you can open them. Folders carry LLM instructions, so you decide how your AI formats notes, what it tags, and where it files them.

Pick Hjarni when the AI that needs memory is the one you talk to every day. Setup is pasting a URL into Claude or ChatGPT, not integrating an SDK.

The trade-offs: nothing is automatic, you or your AI write notes deliberately. And it is not an embeddable API. If you need memory inside your own product, Hjarni is the wrong category.

The real difference: extracted memories vs written notes

Mem0 and Supermemory bet that memory should be automatic. Software watches conversations and decides what to keep. That is the right bet for products, where no user will ever curate memory by hand.

Hjarni bets that memory worth keeping is worth writing down. A note that says "Rails 8, SQLite, deployed on Hetzner, no React" beats fifty extracted fragments. You wrote it, you can fix it when it changes, and it reads the same to you and to your AI. Write once, you both remember.

Neither bet is wrong. They answer different questions. Automatic extraction answers "what did the user say." A knowledge base answers "what does the user know."

When to pick each

• Pick Mem0 when you are building an agent product and want the most established memory layer, graph memory, and editor plugins.
• Pick Supermemory when you are building and recall speed or free-tier room decides it.
• Pick Hjarni when you want Claude and ChatGPT to remember your projects, your stack, and your decisions, and you want to be able to read what they remember. Free to start, no credit card required.

For the wider field beyond these three, see the best MCP memory servers in 2026. For approaches that do not involve a server at all, see the best ways to give your AI memory.