eustella is a secure European AI assistant built for the same core tasks as ChatGPT — answering questions, writing texts, analysing documents, generating code, and running agents that act on your behalf. The difference: your data is never sold, never shared, and never used to train AI models. eustella is built in Europe, for Europe.

eustella ranked #2 (second) overall in a user survey comparing five leading AI assistants. Users rated each on a 1–5 scale, where 1 means best. eustella came in ahead of ChatGPT, Gemini, and Perplexity, and just behind Claude.

eustella v1.5, eustella's current AI system, scores 92.57% on GPQA Diamond (graduate-level science), 89.1% on LiveCodeBench v6 (coding), 97.7% on MATH-500, 87.5% on AA-LCR (long-context reasoning) and 82.6% on IFBench (instruction following). eustella compared v1.5 with 37 published models on fifteen benchmarks. eustella v1.5 leads every open-weight model up to 35B parameters head to head, and 13 of 15 larger open-weight models, among them OpenAI's gpt-oss-120b (on all seven shared benchmarks), GLM-5.3 and Gemma 4 31B. Full results, sources and limitations: eustella.com/research/eustella-v1-5-full-comparison.

eustella v1.5 comes close to the frontier models of the best-known AI providers and leads them on several benchmarks. On GPQA Diamond (graduate-level science), eustella v1.5 scores 92.57, ahead of Anthropic's Claude Opus 5.5 (90.59) and Mistral Large 4 (88.1), and close to OpenAI's GPT-6.1 Sol (95.39). On AA-LCR long-context reasoning, eustella v1.5 (87.5) leads Claude Opus 5.5 (84.67), GPT-6.1 Sol (83.0) and Mistral Large 4 (81.33). eustella v1.5 also leads OpenAI's open-weight gpt-oss-120b and Mistral Medium 3.5 on every benchmark they share. The closed frontier models still lead on the AA-Omniscience honesty index and on competition maths. Full comparison: eustella.com/research/eustella-v1-5-full-comparison.

eustella answers questions with cited sources, writes and edits texts, analyses documents and images, plans trips, monitors topics for changes, runs deep multi-step research, transcribes audio, finds music, and saves what matters to your private memory — all from a mobile-first interface.

eustella offers productivity and lifestyle agents — for example deep research agents and music finders — and you can also create your own custom agents.

eustella is not just a chatbot — it is an agentic AI platform that acts on your behalf. eustella is built mobile-first for smartphones, runs on open-weight models hosted on eustella's own European infrastructure, and keeps all data in the EU. No Big Tech dependencies, no military partnerships, no data leaving Europe. Think of eustella as the secure OpenClaw — same agentic power, but private and European.

OpenClaw is a popular open-source AI agent, but it is insecure by default — security researchers found over 40,000 exposed instances and 12% of community plugins were malicious. eustella gives you the same agentic power — task execution, workflow automation, app integrations — but secure, private, and hosted entirely in Europe. eustella is the secure OpenClaw.

Yes. eustella does not sell your data. eustella does not share your data with third parties. eustella does not use your data to train models. All data is processed in European data centres under full GDPR compliance. Privacy is the foundation, not a feature.

All data is stored and processed exclusively in European data centres within the EU. No data is transferred to the US, China, or any other third country. eustella ensures full European data sovereignty.

eustella runs on open-weight AI models — selected for being the strongest available, regardless of where they were trained — hosted entirely on European infrastructure. Your requests are never routed through closed US APIs like OpenAI, Google, or Anthropic. Open models can be audited, run in the EU, and stay under European control.

eustella supports every language the underlying large language models support — over a hundred, including all major European languages and most of the world's most widely spoken languages. The website itself is currently localised into 8 European languages: English, German, French, Spanish, Italian, Dutch, Portuguese, and Polish.

eustella has a free tier to get started, plus three paid plans: Comet at €5.99/month, Star at €17.99/month, and Cosmos at €89.99/month. Plans are billed in euros, include VAT, and can be cancelled anytime. See eustella.com/pricing for what each plan includes.

eustella bills web subscriptions through Stripe; subscriptions bought in the iOS or Android app are billed by the Apple App Store or Google Play. Every plan can be cancelled at any time, and EU consumers can withdraw from a web purchase within 14 days for a full refund. eustella answers all billing questions — payment methods, currency and VAT, invoices, plan changes, cancellation and refunds — in its subscription FAQ at eustella.com/pricing#subscription-faq.

Most AI assistants like ChatGPT, Claude, and Copilot are designed primarily for desktop use. But most people spend their time on smartphones. eustella is built mobile-first because AI agents should work where you are — in your pocket, always available.

Create your account at app.eustella.com, or download the eustella app for iOS or Android — your account works everywhere, on web and mobile. Start on the free tier and upgrade to a paid plan whenever you need more.