Mnemosphere
Mnemosphere is a multi-model AI research workspace running GPT-5.5, Claude, Gemini, Grok, DeepSeek and Perplexity side by side in one chat. Built for researchers, founders, product managers and analysts, it starts at $25 per month with no free plan.
What is Mnemosphere?
Mnemosphere is an AI research workspace published by Mnemosphere Pte Ltd, a Singapore company. It gathers the frontier models of several vendors into one chat interface, sold under the line the ChatGPT for superhumans. The home page advertises GPT-5.5, Claude 4.6 Sonnet, Gemini 3.1 Pro, Grok 4.2 and Perplexity Sonar as flagship models, with OpenAI o3, Claude Opus 4.7 in Extended Thinking mode and DeepSeek V4 Pro for reasoning work, and promises that every new frontier model is added the moment it ships, at no change of subscription.
The core mechanic is multi-model streaming: up to three models answer the same prompt at once, side by side, and each one knows what the others replied, so a model can be asked to react to another's answer. Models can be added, removed or swapped mid-thread, including in a conversation started with a single model. Parallel Prompts sends several distinct prompts simultaneously. Two one-click actions sit on every answer: Critique, which generates a critical review pointing at missing context, weak assumptions and counter-arguments, and Mindmap, which converts the answer into an interactive map. An inline highlighter persists across the thread, and Thread Notes are hyperlinked back to the exact spot where an idea appears.
Around this sit Lite Threads, Branch Threads, an auto-generated conversation index, Open in New Window, Prompt Assist, configurable Model Identities and PDF export. The workspace also chats with a YouTube video through its transcript, comments and key moments, or with any web page URL, runs several deep researches in parallel across OpenAI, Gemini and Perplexity, and offers web search with cited answers on every model as well as X/Twitter search. Uploads accept PDF, CSV, Excel, images and code files, capped at five attachments per question. Image and video generation are not available: the FAQ answers Not yet and places them on the roadmap.
Access is paid only, from $25 per month, the application running at chat.mnemosphere.ai after signup, while five small tools work without an account. A separate iOS app, Sphere, carries its own legal pages and a Sphere Pro subscription billed by Apple.
What it does
- Query up to three frontier models in parallel on the same prompt and read their answers side by side
- Launch several different prompts at once with Parallel Prompts
- Trigger a one-click critique of any answer: missing angles, weak assumptions, counter-arguments
- Turn any answer into an interactive mindmap in a single click
- Run several deep researches in parallel across OpenAI, Gemini and Perplexity
- Chat with a YouTube video through its transcript and comments, or with any web page from its URL
- Highlight passages, attach notes linked to their exact place in the thread, and export a conversation to PDF
When to use Mnemosphere / When not to
A quick filter to help you decide if Mnemosphere is the right fit.
When to use Mnemosphere
- Heavy LLM users who have outgrown single-model chat and already pay for several AI subscriptions — the publisher claims a unified plan saves up to $55/month in aggregate billing
- Researchers and academics running literature reviews, synthesising multiple sources and comparing competing angles on the same question
- Founders, strategy consultants and product managers who want several readings of the same problem before committing to a decision
- Financial analysts and market researchers whose memos and valuations cannot afford a single model's blind spot
- Policy and regulatory researchers who need bias detection, counter-arguments and cited web answers inside the same thread
When not to use Mnemosphere
- Casual users asking simple one-sentence questions — the publisher itself says the product is more powerful than they require
- Anyone looking for a free or occasional-use tool: there is no free plan and the entry point is $25 per month
- Creators who need image or video generation, which the FAQ still answers with "Not yet"
- Developers wanting programmatic access: no public API and no developer documentation are offered
- Very high-volume users and anyone under 18: quotas stop at 200 messages a month on Pro and 1,000 on Ultra, and the terms require users to be over 18
How to use Mnemosphere
A typical end-to-end flow, from setup to results.
- Pick a plan and create an account from the signup page, which opens the application at chat.mnemosphere.ai; signup works by email or through Google, Facebook, Instagram, Twitter or LinkedIn
- Open a thread and select up to three models to answer your prompt
- Switch on web search before submitting when you need fresh, cited answers
- Attach up to five files per question (PDF, CSV, Excel, images, code) or paste a YouTube or web page URL
- Submit the prompt and compare the answers as they stream side by side
- Add, remove or change models mid-thread, including in a conversation started with a single model
- Use the one-click buttons on any answer: Critique, Mindmap, Open in New Window
- Highlight a passage and send it to Thread Notes, then click a note later to jump back to its source
- Optionally connect Google Drive and Google Sheets to pick source files and export results
- Export a thread as PDF; cancel at any time from Account Settings or by email to hello@mnemosphere.ai
Pros & Cons
Pros
- One subscription covers every frontier model instead of several separate plans; the publisher claims a unified subscription saves up to $55/month in aggregate billing
- New frontier models are added as they ship, without changing plan
- Tooling that single-model interfaces do not offer: critique, mindmaps, parallel prompts, hyperlinked notes, thread branching
- Cross-model awareness — one model can be asked what it makes of another model's answer
- No training on customer data, stated without reservation in the FAQ
- 14-day money-back guarantee on a first purchase, two months free on annual billing, and cancellation at any time with access kept until the end of the current period
- Five AI tools usable without an account, and a public endorsement from Chris Messina, #1 Hunter on Product Hunt
Cons
- No free plan at all: the entry ticket is $25 per month
- Message quotas cap usage at 200 per month on Pro and 1,000 per month on Ultra
- The Ultra price is not published in static HTML — the pricing block is rendered in JavaScript, so only the $25/month entry point can be checked without an account
- No public API, and neither image nor video generation ("Not yet"); the Enterprise plan is only announced as coming soon
- No DPA, no EU representative under Article 27, no named DPO, and no data hosting country or region disclosed
- Targeted advertising on personal data is declared in the privacy policy (Google, Facebook, Instagram, Twitter, LinkedIn, Reddit)
- Mobile is iOS only through the separate Sphere app, with no App Store link published on the site and no Android version; support runs mainly through a form, with a single hello@ address for support, legal and GDPR matters
Pricing & Plans
There is no free plan. Mnemosphere is sold by subscription only, starting at USD 25.00 per month; the FAQ states plainly that it is a professional tool with paid plans only, starting at $25/mo. Two tiers are named, Pro and Ultra, but only the entry point is published: the pricing block is rendered in JavaScript and the Ultra amount does not appear in the page. Annual billing is offered with two months free. Payments are handled by Paddle as Merchant of Record, by credit card, PayPal or another method it supports. A 14-day money-back guarantee covers a first purchase, and the subscription can be cancelled at any time, access being kept until the end of the current billing cycle with no prorated refund. An Enterprise plan is announced as coming soon, and the Sphere Pro subscription of the iOS app is billed by Apple at an amount that is not published.
- Pro — access to all frontier models
- Multimodel Chat
- Parallel Prompts
- Instant Mindmaps
- Inline Highlighter and Notes
- Critique
- YouTube Video Intelligence
- up to 200 messages per month
- Ultra (marked "Recommended") — everything in Pro plus Multi-Model Deep Research
- Pro Mindmaps
- Lite Threads
- up to 1
- 000 messages per month
- personalised support and priority access to experimental features
- 14-day money-back guarantee
- $25 per month ("Plans start from $25/mo")
- the amount of each individual tier is not published in the static page
- two months free
- Enterprise — announced as "Coming soon"
- contact through hello@mnemosphere.ai
- Sphere Pro — in-app subscription of the iOS app Sphere
- billed by Apple
- amount not published
Data, GDPR & hosting
A consolidated view of how Mnemosphere handles your data.
GDPR overview
The privacy policy carries a dedicated EU Data Subject Rights section for EEA residents, listing access, rectification, erasure, restriction of processing, portability, objection to processing and the right to lodge a complaint with a supervisory authority, with an announced response time of 30 days. Californian CCPA/CPRA rights are covered separately. Beyond that, implementation is thin: no EU representative under Article 27 is designated in the legal pages, no Data Protection Officer is named, the single contact point is hello@mnemosphere.ai, and no data processing agreement is published or offered on request. Transfers outside the user's own jurisdiction are explicitly assumed. The company is established in Singapore and the terms apply Singapore law, while stating that EU consumers keep the mandatory provisions of the law of their country of residence.
Who owns the data?
Mnemosphere's terms leave ownership of uploaded content with the user, who must warrant that the content is theirs or that they have the right to use it. In exchange, creating, uploading, posting, sharing or storing content grants the publisher a worldwide, non-exclusive, royalty-free license to use, reproduce, modify, adapt, publish, translate, create derivative works from, distribute, and display such content, bounded by its stated purpose: providing and improving the Service. The privacy policy counts conversations, chat content, files and attachments as Usage Data collected by the company. Users can update, change or delete their information from account settings, and the FAQ states that none of it is ever used to train a model.
Reuse rights
Personal data is used to provide and maintain the service, create and manage the account, perform the contract, contact the user, handle requests, analyse usage and improve the product, and it may change hands in a corporate transfer. To produce answers, prompts, conversation content and relevant attachments are transmitted to the publisher's backend and to third-party AI model providers. Data is also shared with service providers, affiliated companies, business partners and, where relevant, with the user's consent. The privacy policy openly declares targeted advertising through Google Adwords, Facebook, Instagram, Twitter, LinkedIn and Reddit ads, along with analytics through Google Analytics and Mixpanel on the web — Mixpanel including session recording — and PostHog in the iOS app, plus invisible Google reCAPTCHA for fraud prevention. Do Not Track signals are honoured for third-party advertising and marketing, but product analytics continue. The company states that it does not sell personal information as defined under the CCPA/CPRA.
Data retention & training
Hosting summary
No hosting country or region is disclosed anywhere in the published pages. The privacy policy only states that information, including personal data, is processed at the Company's operating offices and in any other places where the parties involved in the processing are located, and it explicitly assumes transfers outside the user's own jurisdiction. The jurisdiction that can be established is Singapore: the publisher, Mnemosphere Pte Ltd, sits at 14-04, 160 Robertson Road, Singapore 068914, both the privacy policy and the terms define Country as Singapore, and Singapore law governs the contract. Infrastructure providers are named without any location — Supabase for authentication, RevenueCat for iOS subscriptions, PostHog for iOS analytics, unnamed cloud infrastructure providers, and the third-party AI model providers that receive prompts. Payments are processed by Paddle acting as Merchant of Record. The domain resolves to 216.239.38.21, a Google anycast address, which points to a CDN node and says nothing about where data is stored. In short: Singaporean law, undocumented physical location, and no data processing agreement on offer.
Things to keep in mind
Risks and trade-offs to weigh before adopting Mnemosphere.
- Targeted advertising on personal data is explicitly declared in the privacy policy — Google Adwords, Facebook, Instagram, Twitter, LinkedIn and Reddit ads — and Mixpanel additionally records user sessions.
- The terms take a worldwide, non-exclusive, royalty-free licence on uploaded content, covering modification, derivative works, distribution and display: read that clause before uploading anything confidential.
- Prompts and attachments are transmitted to third-party AI model providers to generate answers, and no hosting country or region is disclosed anywhere on the site.
- No DPA, no EU representative under Article 27, no named DPO and no formal subprocessor list — providers are only cited in passing with "such as", which is explicitly non-exhaustive.
- The Ultra price cannot be read without an account since the pricing block is rendered in JavaScript; the 14-day guarantee covers only the very first payment, renewals are not refundable, and liability is capped at the amount paid or $100.
- The model version numbers advertised on the home page (GPT-5.5, Claude 4.6, Gemini 3.1, Grok 4.2) are publisher claims that are not independently verified, and the terms date from 30/04/2025, more than a year behind the privacy policy.
- Reading three confident answers side by side can feel like verification when it is not: agreement between models is not evidence, and the one-click critique is itself generated. The comfort of a well-formed synthesis makes it easy to stop reading sources and to let the workspace do the judging.
Setup & Integrations
Technical difficulty
Very easy, with one catch: it is paid from the start. Nothing to install on the web: you sign up by email or through Google, Facebook, Instagram, Twitter or LinkedIn, pick Pro or Ultra during signup, and the workspace opens at chat.mnemosphere.ai. No API key, no connector and no technical configuration are required; Google Drive and Google Sheets can be linked by OAuth if wanted. The iOS app, Sphere, is installed separately and signs in with Apple or Google. The five tools on the tools page need no account, and the publisher claims no prompt-engineering skills are needed.
Deployment
Integrations
Behind Mnemosphere
Social
Resources
All the official URLs gathered for verification and reference.
Alternatives
Tools that compete with or complement Mnemosphere.
Frequently asked questions
Which AI models does Mnemosphere support?
Is there a free plan?
Why not use ChatGPT, Claude or Gemini directly?
What files can be uploaded?
How does multi-model streaming work?
Can Mnemosphere generate images or video?
Is my data used to train AI models?
How does the refund work?
Is there a mobile app?
Who publishes Mnemosphere, and is there a minimum age?
Should you pick Mnemosphere?
Mnemosphere makes a simple bet: one subscription instead of several, plus tooling that single-model chat interfaces do not offer. Multi-model comparison, parallel prompts, one-click critique, mindmaps and hyperlinked thread notes are genuine differentiators for people whose work is about weighing several angles rather than getting a quick answer. The audience is narrow and openly stated — researchers, founders, product managers, consultants, financial and policy analysts — and the publisher concedes that the product is more powerful than casual users need and that its advanced features take a short learning curve.
On trust, the strongest point is the flat statement that prompts, uploads and chats are never used to train any model. The weak points are documentary: no DPA, no EU representative under Article 27, no named DPO, no hosting country or region disclosed, and targeted advertising on personal data declared in the privacy policy. The terms also take a broad worldwide, royalty-free licence on uploaded content, framed as necessary to provide and improve the service.
Pricing is only partly transparent. The $25 per month entry point is published in plain HTML in three places, but the pricing block is rendered in JavaScript and the Ultra amount appears nowhere in the page, so the top of the range cannot be checked without an account. There is no free plan, and the 14-day money-back guarantee covers a first purchase only.
The publisher is young: the domain was registered on 09/04/2024 and first archived on 16/04/2024. Legal documents are unevenly maintained, the terms dating from 30/04/2025 against a privacy policy updated on 20/02/2026. Worth the money for heavy users who really do compare models; hard to justify for anything lighter.
- Choosing a selection results in a full page refresh.
- Opens in a new window.