Remote MCP servers for personal context: Sensefold, Mem0, Supermemory, Readwise, and Raindrop compared

Five hosted MCP servers give an AI client access to what a person has saved, written, or remembered: Mem0, Supermemory, Readwise, Raindrop.io, and Sensefold. As of September 13, 2026, all five implement OAuth 2.1 with PKCE and open dynamic client registration. They differ in what they store, how an agent's access is bounded, what happens when an agent deletes or edits, whether you can run them yourself, and who is allowed to connect.

Sensefold wrote this page and appears in it, so every cell says how it was checked. Probe is an unauthenticated request against the production endpoint, reproducible with the curl at the end. Live is an OAuth connection from a throwaway MCP client to a real account on each service, recording the consent screen, the scope granted, and what tools/list returned. Tested is the write, conflict, and delete cycle, which we ran only against our own server. Docs is the vendor's own documentation or pricing page, read on the review date. The section on where Sensefold is weaker is not short.

Three architectures, not five versions of one product

Remote MCP servers for personal context come in three shapes. Memory engines such as Mem0 and Supermemory extract facts from conversations and documents and return the facts. Document libraries such as Sensefold and Readwise store the full text of what you read, and in Sensefold's case what you wrote and what you discussed with an AI, and return the documents. Bookmark managers such as Raindrop.io index URLs, tags, and collections and return bookmarks.

That difference explains most of the tables below. A revision history makes sense for a document store and is beside the point for a store of extracted facts. An SDK makes sense for a memory engine that developers embed in their own product and is beside the point for a reading app. Read each row with the shape in mind.

Comparison

Two tables, split so each fits a screen. Cells are short on purpose; the sections below carry the detail and the sources. "Not documented" means the vendor's documentation on the review date did not say, not that the feature is absent.

Shape and access

Recovery, source, portability, price

Sources: Mem0 MCP docs, pricing, GitHub; Supermemory MCP overview, self-hosting, pricing, GitHub; Readwise MCP docs, pricing; Raindrop.io developer docs, help page, export; Sensefold MCP tools reference, permissions, pricing. Star counts are from the GitHub API on the review date.

Authentication: interactive OAuth and headless keys

All five remote MCP servers support OAuth 2.1 with PKCE for interactive clients like Claude, ChatGPT, and Cursor. Headless automation differs sharply: Mem0 and Raindrop.io accept standard API tokens, Sensefold issues tiered Agent keys with fixed permissions, while Readwise and Supermemory document browser-based OAuth flows exclusively for their hosted MCP endpoints.

Two details matter in practice. Readwise's registration response echoes only the authorization_code grant, and its 401 body instructs clients to clear tokens and reconnect, requiring re-authorization rather than token refresh. Supermemory advertises identity scopes exclusively; read versus write permissions are not expressed at the OAuth layer, but are determined by which spaces you select.

Access boundaries: can you restrict an agent to reading?

We connected a throwaway client to each service and looked at the consent screen. Mem0 asks which organization and project; there is no read or write choice, and the token came back with read write. Readwise lists what the client will be able to do, including create, modify, and delete, with no choice, and granted read write openid. Supermemory's screen is the richest: a workspace picker, a Read and write or Read only toggle, and an All memories or Only some tags scope. Sensefold asks for one of three access levels and defaults to Read only. Raindrop.io was not tested live because its MCP needs a Pro plan.

Choosing read-only is one thing; what the server does with it is another. With Supermemory's Read only selected, tools/list still returned all 15 tools including add_memory and save-memory, and whoAmI reported permission: write, but an actual add_memory call was refused with HTTP 403 and the message "This API key has read-only access". So the boundary is real, it is enforced at the API, and it is invisible to the client until a write fails. Sensefold's boundary is visible: the Read only connection listed exactly 6 tools, Edit listed 10, Full listed 11, and calling save_note on the read-only connection or delete_item on the edit connection returned "Tool not found", because out-of-tier tools are not registered for that connection; a dispatch-layer check with API_KEY_TIER_DENIED sits behind that as a second gate. Mem0 and Readwise offered no read-only option to test.

Write recovery: what an agent's mistake costs

Write recovery is where the five diverge most, and the shape of the store decides what recovery even means. We ran the cycle on Sensefold over MCP with a full-tier connection: save_note created a note at version 1; update_note with a stale expectedVersion was refused with HTTP 409 VERSION_CONFLICT and the current version in the message; the same call with the right version moved it to 2, and update_tags to 3; delete_item with a stale version was refused the same way, with the right version returned deleted: true, and a second delete returned alreadyDeleted: true; get_item afterwards returned 404. The web app's Activity page then listed Created, Edited, Changed tags, and Deleted for that note with the actor shown as AI, each openable to inspect or roll back. Raindrop.io routes deletes to Trash and deletes permanently only from Trash. Mem0 exposes delete_memory, delete_all_memories, and delete_entities with a list_events log and no documented revert. Supermemory has no delete tool; forgetting is an add_memory call with action: forget. Readwise documents a highlight delete and no Reader document delete.

For a store of extracted facts, an event log may be the right primitive: memories are appended and superseded, and nobody diffs them by hand. For a library of documents you wrote, a version you can revert is the primitive that matters. Ask the vendor three questions: is delete soft, is there a version to go back to, and can two writers collide silently. Only one column above answers all three in its documentation, and it is ours, which is why the next section exists.

Open source, self-hosting, and developer tooling

Mem0 and Supermemory are open source and can run on your own machine: Mem0 under Apache-2.0 with a self-hosted OSS edition alongside the managed Platform, Supermemory under MIT with a single-binary local edition. Both ship Python and JavaScript SDKs and integrations for agent frameworks. Readwise, Raindrop.io, and Sensefold are proprietary hosted services. Raindrop.io has a public REST API; Sensefold reaches agents through MCP only; Readwise's MCP documentation covers only the MCP interface.

If data sovereignty, local execution, or embedding memory in your own product is the requirement, the choice is between Mem0 and Supermemory and the other three are not candidates.

Plan gates

Mem0's Hobby plan is free, and a fresh Hobby account authorized against the hosted MCP and listed all 11 tools. Supermemory's Free plan carries $5 of credits a month, and a fresh Free account authorized and listed all 15 tools; only the write was refused, and only because we chose Read only. A fresh Readwise account on its 30-day trial authorized and listed 22 tools. After the trial, Readwise's full plan is the inferred requirement, since Lite excludes Reader and the MCP docs do not name a plan. Raindrop.io's MCP is a Pro feature in beta. Sensefold has no free plan: saving is free, AI runs on credits, Starter is $16 a month or $160 a year after a 14-day trial with a card.

Which one fits

Choose Mem0 if you are building an application that needs memory per user or per agent and want SDKs, open source, and a free developer plan. Choose Supermemory if you want extracted memory with shared spaces, a local option, and in-conversation widgets such as guided save and a memory graph. Choose Readwise if you live in Reader and want its documents and highlights reachable; Readwise exposes highlights over MCP, and Sensefold's MCP responses do not carry highlights today. Choose Raindrop.io if a bookmark manager is the library you already keep. Choose Sensefold if the thing you want your AI to read is the full text of what you read, watch, discuss with an AI, and write down, and you want the agent's writes tiered, versioned, and revertible.

Where Sensefold is weaker

Sensefold is proprietary with no self-hosted edition; Mem0 and Supermemory have both. It has no SDK and no REST API for third parties; Mem0 and Supermemory have SDKs and Raindrop.io has a REST API. It is single-user with no shared spaces; Supermemory is built around them. It does not extract facts; it stores documents and notes and searches them, which is a different tool for a different job. It has no free plan; Mem0 and Supermemory do. Its MCP ecosystem is a single server with a small community; Mem0's has 65,000 stars behind it. Its highlights and clip comments exist in the apps but are not part of its MCP responses today, while Readwise and Raindrop.io expose highlights as MCP tools. And save_link spends credits because it runs enrichment, while reads and notes do not.

Reproduce the probes

Anyone can verify the transport and authorization metadata reported in this article without creating an account. The bash script below executes unauthenticated HTTP requests against each production endpoint, querying the MCP initialize method, OAuth protected-resource discovery, and OAuth authorization-server metadata to confirm HTTP 401 statuses, PKCE support, and advertised scopes.

probe() {
  u=$1; h=$(echo "$u" | sed -E 's#(https://[^/]+).*#\1#')
  curl -s -D - -o /dev/null -X POST "$u" \
    -H "Content-Type: application/json" \
    -H "Accept: application/json, text/event-stream" \
    -d '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"probe","version":"0"}}}' \
    | grep -iE "^HTTP|www-authenticate"
  curl -s "$h/.well-known/oauth-protected-resource/mcp" || curl -s "$h/.well-known/oauth-protected-resource"
  curl -sL "$h/.well-known/oauth-authorization-server"
}
probe https://mcp.mem0.ai/mcp
probe https://mcp.supermemory.ai/mcp
probe https://mcp2.readwise.io/mcp
probe https://api.raindrop.io/rest/v2/ai/mcp
probe https://api.sensefold.app/mcp

Dynamic client registration is a POST to the registration_endpoint from that metadata with a client name and a loopback redirect URI. It creates a public client record, which is what your MCP client does on first connect.

FAQ

Can I connect one remote MCP server to Claude, ChatGPT, and Cursor at the same time?

Yes, for all five. Each is one remote server that several clients authorize against separately over OAuth, so the same library or memory store is reachable from every client. Sensefold documents that each connection carries its own tier, and Supermemory allows scoping access by space.

What is the difference between Mem0 and a document library like Sensefold or Readwise?

Mem0 returns facts it extracted from conversations, keyed by user, agent, app, or run, and is meant to be embedded in an application. Sensefold and Readwise return the documents themselves, the full text of pages, notes, or highlights a person saved, for that person's own AI clients.

Which of these has a free plan?

Mem0's Hobby plan is free with 10,000 add and 1,000 retrieval requests a month, and Supermemory's Free plan includes $5 of credits a month; we connected fresh accounts on both. Readwise works during its 30-day trial and then needs the full plan. Raindrop.io gates the MCP behind Pro. Sensefold has no free plan and starts with a 14-day trial.

Can I limit an agent to read-only access?

Sensefold and Supermemory both offer it at the consent screen. Sensefold's read_only connection lists only the six read tools; Supermemory's Read only grant still lists the write tools but refuses writes with a 403. Mem0 and Readwise offered no read-only choice when we connected. Raindrop.io labels tools read-only or modifying in its docs and was not tested.

Can an agent delete my whole library through an MCP connection?

Mem0 exposes delete_all_memories, so yes by design there. Raindrop.io and Sensefold route deletes to Trash or a recycle bin first, and Sensefold documents that connected agents cannot delete items permanently.

Which personal context MCP servers can be self-hosted?

Mem0 and Supermemory. Mem0 ships an open-source self-hosted edition under Apache-2.0; Supermemory ships a single-binary local edition under MIT. Readwise, Raindrop.io, and Sensefold are hosted only.