Which AI memory system has the largest context window in 2026?

Gemini 2.5 Pro leads on context window at 1M+ tokens; Claude follows at 200k; GPT-5-class models are at 128k-256k depending on tier. But context window is not the same as persistent memory — a large window only helps within one chat. For cross-chat persistence, the comparison flips: ChatGPT Memory and dedicated memory layers like Konshus matter more than raw token capacity.

Which AI lets you export everything you've stored?

OpenAI and Anthropic both offer full data exports via Settings → Data Controls (delivered as a ZIP within hours to days). Google Gemini exports through Google Takeout. Character.ai and Replika offer GDPR-driven exports but no one-click bulk option. Konshus offers full export on every tier, including free, as a policy commitment.

Do any AI memory systems survive a model swap?

Within a provider, sort of — your saved memories carry over but recall behavior can shift with each new model. Across providers, no — there is no migration tool, and providers have no incentive to make memory portable to competitors. The only systems that survive cross-provider swaps by design are dedicated memory layers and personal context documents.

What does encryption-at-rest actually mean for AI memory?

It means the company storing your memory has scrambled the data such that even if the storage is breached, the raw text cannot be read without the key. It does NOT mean the company itself cannot read it (they hold the key). For sensitive data, look beyond encryption-at-rest to: training-use policy, third-party-share policy, human-review disclosure, and hard-delete with audit.

How often is this comparison updated?

Updated June 2026. We re-check provider docs, pricing, and policies quarterly because this category changes fast — model releases, deprecations, and policy updates routinely invalidate older comparisons.

Benchmark · 14 min read · Updated June 2026

AI Memory Systems Compared: The Definitive 2026 Benchmark

Eight major AI memory systems, twelve axes of comparison, one uncomfortable conclusion: most of them aren't designed to remember you across the next model release. Here's the full benchmark, with sources, and a clear read on what to use when memory actually matters.

Eight AI memory systems represented as connected nodes

TL;DR

Best in-app memory: ChatGPT Memory (mature, capped, OpenAI-only). Best context window: Gemini 2.5 Pro (1M+ tokens, session-only). Best scoped persistence: Claude Projects (explicit, narrow). Best portability: Personal context doc (free, manual) and Konshus (dedicated, automated). Avoid for sensitive data: any platform that doesn't clearly answer the four storage questions below.

The full comparison table

System	Context window	Saved memory	Cross-provider	Survives swap	Encryption	Hard delete	Used for training?	Export	Price	Notes
ChatGPT (Memory)	128k-256k	~few hundred items	No	Partial	Yes (provider)	Yes, 30-day	Opt-out on consumer	Full ZIP	$0-$200/mo	Most mature consumer memory; opt-in.
Claude (Projects + Memory)	200k	Per-project docs	No	Yes inside Claude	Yes (provider)	Yes	Free may train; paid no	Full ZIP	$0-$200/mo	Explicit, curated, no auto-learn.
Gemini	1M+	Small saved-info list	No	Unclear	Yes (Google)	Yes (Takeout)	Workspace excluded	Takeout	$0-$20/mo	Huge context, weak persistence.
Character.ai	~8k free / larger c.ai+	Pinned memories	No	No — filters reshape	Yes (provider)	Yes	Yes (subject to ToS)	Manual	$0-$10/mo	Personality drifts with model changes.
Replika	Rolling window	Memory Library	No	No	Yes (provider)	GDPR export/delete	Per policy	GDPR export	$0-$80/yr	2023 wipe is the cautionary tale.
Perplexity	Per-thread	Spaces + profile	No	Yes within Perplexity	Yes (provider)	Yes	Pro has controls	Per-answer	$0-$20/mo	Research-shaped, not ambient.
Personal context doc	Whatever model allows	Whatever you write	Yes	Yes	Wherever you store it	Yes, instantly	N/A	It IS the export	Free	Manual but bulletproof.
Konshus (vault)	Model-agnostic	50 → ∞ atoms by tier	Yes — all major providers	Yes by design	Per-artifact at rest	Hard-delete + audit	Never	Full export every tier	$0-$599/yr	Built around portability as the core promise.

Source: provider documentation as of June 2026. Specifics shift; re-check before relying on any single number.

The four questions every storage system has to answer

Before storing anything meaningful in an AI memory system, get a clear answer to all four. If any answer is "unclear" or unfavorable, don't store sensitive content there.

Where is it stored? Which provider, which country, which jurisdiction.
Who can access it? Internal employees, contractors, third parties, law-enforcement requests.
Can you delete it for real? With an audit trail, not just hidden from your view.
Is it used to train? The default for consumer tiers is often yes unless you opt out.

Why the "survives swap" column matters most

The single biggest difference between memory systems isn't capacity or price — it's whether the memory survives the next model release. We have lived through GPT-3.5 → 4 → 4o → 5, Claude 2 → 3 → 3.5 → 4, Gemini 1 → 1.5 → 2 → 2.5, the Replika February 2023 wipe, and the Character.ai filter changes. Every one of these events broke continuity for some users.

Systems where memory survives a swap have one thing in common: the memory lives outside the model. Personal context documents survive because you control them. Dedicated memory layers survive because they're model-agnostic by design. Everything inside one provider's app is at the mercy of that provider's next release.

Never lose your AI again

Konshus is one way to solve this — a persistent memory vault and portable persona that follows you across ChatGPT, Claude, Gemini, and whatever ships next.

Meet Konshus

When to use which

Casual single-app user: turn on ChatGPT Memory or Claude memory, prune monthly, accept the cap.
Scoped knowledge work: Claude Projects or Perplexity Spaces.
Long single-session research: Gemini 2.5 Pro for the context window.
Privacy-first solo: a personal context document in a notes app you control.
Heavy multi-model user: a dedicated memory layer like Konshus that holds the persona separately from any app.
AI companion bond: Replika-style — export quarterly, keep a private lore document, never assume the platform won't change.

Related deep dives

Frequently Asked Questions

Never lose your AI again

Konshus is one way to solve this — a persistent memory vault and portable persona that follows you across ChatGPT, Claude, Gemini, and whatever ships next.

Meet Konshus