MemorySync vs OpenAI Memory
Compare MemorySync with OpenAI’s conversation state, the Conversations and Responses APIs that replaced the Assistants API, and with ChatGPT’s memory.
Capabilities side by side
| Capability | MemorySync | OpenAI Memory |
|---|---|---|
| Memory scope | Per end user, across every conversation, session and tool | Per conversation; nothing carries across conversations unless your code copies it |
| What is kept | Facts extracted from each write | The conversation’s items as sent: messages, tool calls and their outputs |
| Retention | Until you delete it, or until a TTL you set expires | Conversation items are kept until you delete the conversation |
| Scoping | End user required on every API-key call; every read, search and delete is filtered to that end user and project | A conversation is an object in your API project; which end user it belongs to is up to your code |
| Models | Any model: retrieved facts go into your prompt | Used by OpenAI models through the Responses API |
| Portability | Export through the API; import from other providers with the CLI | Conversation items can be listed through the Conversations API |
The OpenAI Memory column states only what OpenAI Memory publishes about itself, checked on 29 September 2026. Sources: Deprecations (Assistants API) · Assistants migration guide · Conversation state · ChatGPT memory. MemorySync figures come from our own production measurements and documentation. Capability tables age quickly: if anything here is out of date, tell us at team@memorysync.io and we will correct it.
Why teams choose MemorySync
- Memory about each end user carries across conversations, sessions and tools. OpenAI’s Conversations API keeps state for one conversation at a time.
- The memory layer is independent of the model provider, so you can switch between OpenAI, Anthropic, Google and open-source models without moving it.
- Stores extracted facts rather than a growing transcript, so a prompt carries the few facts a task needs instead of the whole history.
Moving from OpenAI Memory
- 1
List the items of the conversations you want to keep through the Conversations API.
- 2
Send each conversation’s turns to MemorySync for the end user they belong to, with history append or add; the facts are extracted for you.
- 3
Before each response, query MemorySync for the end user and put the returned facts in your instructions or input. The model call itself does not change.
Common questions
Doesn’t OpenAI’s API handle memory for me?
Within one conversation, yes: the Conversations API keeps the conversation’s items so you do not resend them. It does not build memory about an end user across different conversations, which is what MemorySync stores. The Assistants API and its Threads, which did the same per-conversation job, were shut down on 26 August 2026.
Is ChatGPT memory available to my application?
Not through the API. Saved memories and chat history belong to the ChatGPT app and its users; an application built on the API keeps its own memory about its users, which is the job MemorySync does.
Can I use MemorySync alongside OpenAI models?
Yes. Query MemorySync for the end user, put the returned facts in your instructions or input, and call the Responses API as usual.
Comparisons
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