Published July 6, 2026 · Facts last verified July 6, 2026
Duck.ai, Venice AI, and Proton Lumo are the three names that come up first whenever someone asks for a private alternative to ChatGPT — and they are genuinely different products, not three flavors of the same idea. This comparison is deliberately neutral: each tool wins a category outright, and the right choice depends on which category is yours.
Disclosure: this page is published by Secret Chat AI — a private AI assistant and multi-model gateway, which competes in the same space (our own head-to-heads are here). The three tools below are compared on their own merits.
A one-paragraph definition, since the term gets stretched: a private AI chatbot is one where your conversations are not used for model training, retention is zero or user-controlled, and the link between prompts and your identity is minimized or removed. All three tools here meet that bar — by three completely different mechanisms.
At a Glance
| Criterion | Duck.ai | Venice AI | Proton Lumo |
|---|---|---|---|
| Privacy mechanism | Anonymizing proxy: IP and identity stripped before prompts reach model providers | Hardware-secured inference; no server-side chat storage (history in your browser) | Zero-access encryption: stored chats are ciphertext even Proton cannot read |
| Account required | No | Optional (free tier); account for paid | No for a limited guest chat; account needed for saved, encrypted history |
| Models | Mid-size commercial + open models (GPT-5.4 mini/nano, Claude 4.5 Haiku, Mistral Small, gpt-oss, Gemma); bigger models on paid DuckDuckGo plans | Open-weight catalog (Llama-family, DeepSeek, GLM and others), uncensored | Open-weight models run on Proton's own European servers |
| Who runs inference | The upstream model providers (anonymized, no-training agreements; zero-retention terms, with short caching and abuse/legal exceptions) | Depends on the privacy mode: Venice's own infrastructure for Private/TEE/E2EE, third-party providers under Anonymous | Proton's own infrastructure (Switzerland/EU) |
| Training on your chats | No (contractual) | No (architectural) | No (architectural + policy) |
| Content policy | Standard provider policies | Uncensored by design | Standard |
| Image generation | Yes | Yes | Yes (create, edit and analyse) |
| Open source | No (proxy architecture documented) | Partially (open-weight models; platform proprietary) | Yes (clients) |
| Price | Free; paid DuckDuckGo subscription for advanced models | Free tier; paid tiers (Pro / Pro Plus / Max) | Free tier; Lumo Plus $12.99/month |
Duck.ai: Best Zero-Friction Anonymity
The pitch: open duck.ai, type, get an answer — no account, no cost, no logs. DuckDuckGo's proxy strips your IP and identity before prompts reach OpenAI, Anthropic, or Mistral, and its agreements bar providers from training on the traffic and cap retention at 30 days. Chats are saved only on your device.
Strengths: the lowest possible barrier; a decade-long no-logs institutional reputation behind it; real commercial models (in mini/small variants) rather than only open weights.
Weaknesses: the free models are deliberately mid-size — good for everyday questions, noticeably limited for hard reasoning or long documents; file uploads are not supported at all; the free Sync & Backup does now sync them across devices, end-to-end encrypted and without an account, but it is opt-in and off by default.
Choose it if you want anonymous, free, casual AI chat with the least setup on earth.
Venice AI: Best for Uncensored Open Models
The pitch: private AI without content restrictions. Venice (founded 2024 by Erik Voorhees) started as an open-weight catalog — Llama-family, DeepSeek, GLM and more — and has since added frontier models (GPT, Claude, Gemini, Grok) alongside them, across four privacy modes. Read the mode, not the brand: under Anonymous Venice's own documentation says the provider sees and likely saves your prompt, Private relies on contractual no-storage commitments, and only TEE and E2EE are hardware-enforced. It stores conversations only in your browser, and adds image generation. It is the tool for people who object to both surveillance and guardrails.
Strengths: in its TEE and E2EE modes, the strongest inference-step privacy of the three architectures here — hardware-enforced rather than promised; no refusals on legitimate-but-sensitive topics; creative features (image generation); a broad and fast-moving model catalog.
Weaknesses: the privacy guarantee now varies by mode rather than applying across the board, and the strongest modes carry a smaller model selection — so "I use Venice" no longer says by itself what happened to your prompt; the crypto-adjacent ecosystem (staking, tokens) is a plus for some and noise for others.
Choose it if creative freedom matters to you and you are willing to pick the privacy mode deliberately — its TEE and E2EE modes are the strongest inference-time guarantee on this page.
Proton Lumo: Best Confidentiality Guarantee
The pitch: the Proton Mail treatment applied to AI. Conversations are stored under zero-access encryption — Proton's servers hold ciphertext they cannot decrypt — the clients are open source, nothing trains on your data, and inference runs on Proton's own European hardware, so no third-party provider ever appears in the chain. Free tier available; Lumo Plus is $12.99/month.
Strengths: the strongest storage guarantee in consumer AI; single accountable Swiss operator; open source; GDPR-native jurisdiction.
Weaknesses: capability is a step behind the frontier, since Lumo runs open models on Proton's own hardware rather than reselling GPT or Claude; the free tier is tightly metered (limited messages, history, image generations and a single Project); responses can be slower on intensive tasks.
Choose it if confidentiality is the requirement and you accept a capability trade-off — journalists' sources, health matters, anything where "even the operator can't read it" is the point.
Verdicts by Use Case
| You are… | Best fit |
|---|---|
| Asking casual questions, want zero setup and zero cost | Duck.ai |
| Writing fiction or researching topics mainstream models refuse | Venice AI |
| Handling material where even the operator must not be able to read stored chats | Proton Lumo |
| Doing professional work that needs frontier models (GPT, Claude, Gemini) with a privacy layer | None of the three — that is the gap Secret Chat AI exists to fill; see our head-to-heads |
| Unwilling to let any cloud see prompts at all | A local model — see self-hosting explained and what it really costs |
Frequently Asked Questions
- Which is the most private: Duck.ai, Venice AI, or Proton Lumo?
They protect different stages. Lumo has the strongest storage guarantee (zero-access encryption). Venice has the strongest inference story among these clouds (hardware-secured, nothing stored server-side). Duck.ai has the strongest identity story (no account exists at all). Rank them by which stage your threat model cares about.
- Are all three really free?
All three have usable free tiers. Paid unlocks: bigger models on Duck.ai (via DuckDuckGo's subscription), higher limits and more models on Venice, and Lumo Plus at $12.99/month for more usage and features.
- Do any of them train on my conversations?
No — that is the point of all three. Duck.ai bars it contractually with upstream providers; Venice and Proton never ship your chats to a third party in the first place and commit to no training on their own infrastructure.
- Why would anyone still use ChatGPT directly, then?
Model quality and features. The frontier models are ahead of everything the three tools above can offer, which is exactly the trade-off this category keeps wrestling with — and the gap a privacy gateway to the frontier models tries to close. The retention side of that decision is documented in our 2026 data-retention audit.
Sources
Competitor claims on this page were checked against each company's own documentation on 19 August 2026.