By the end of this post, you’ll know the seven prompt security mistakes beginners make, why each one puts your data at risk, and exactly how to fix it.
What are the most common prompt security mistakes beginners make?
The most common mistakes beginners make are sharing secrets or work data in chat, leaving training toggles on, pasting untrusted text, uploading sensitive files, and assuming chats are private. Each one quietly hands your data to someone else — usually a company, sometimes an attacker. Fixing them takes minutes, not hours.
1. Pasting passwords and API keys into chatbots
Pasting real passwords, API keys, or other secrets into a chatbot is a critical security error — the moment you hit send, you lose control of that secret. OWASP identifies sensitive-information disclosure as a major risk from prompt misuse (OWASP LLM01:2025). Fix: Never type real credentials. Use placeholders like [API_KEY_HERE] when asking for code help, or use a local model like Ollama for sensitive queries.
2. Sharing confidential work data without realizing it
Employees often paste proprietary code, financial reports, or unreleased plans into public chatbots, leading to data leaks. Samsung banned ChatGPT in May 2023 after employees pasted confidential data in three separate incidents within three weeks (TechCrunch). Fix: Ask yourself, “Would I post this on Twitter?” If not, don’t paste it.
3. Never toggling off “Improve the model for everyone”
Many chatbots train on your conversations by default. Leaving this on means your data can be used to train future AI models. OpenAI allows you to turn this off in Settings > Data Controls (OpenAI Data Controls FAQ). Fix: Go to your chatbot’s settings today and turn off any “Improve the model for everyone” or similar toggle.
4. Copy-pasting emails and web pages with hidden instructions
Pasting untrusted text from emails or websites can inject malicious commands into a chat session, a top security risk called prompt injection (Simon Willison). The AI may then silently follow instructions the other person embedded, overriding what you actually asked for. Fix: Only paste text you have created or fully trust. For research, use built-in browser extensions or specialized tools.
5. Uploading sensitive documents without a second thought
Uploading tax forms, legal contracts, or personal IDs to a consumer chatbot risks exposing that data. Consumer chatbots often use uploaded content for training unless you have an opt-out (Anthropic Consumer Privacy). Fix: Redact all sensitive information (names, numbers, signatures) before uploading a document for analysis.
6. Mixing work and personal accounts
Using the same chatbot account for personal shopping and work projects blurs data boundaries. Work data could be exposed in a personal account breach, and vice-versa. Commercial plans like Claude for Work do not train on your data by default, but consumer plans often do (Anthropic Commercial Privacy). Fix: Keep separate accounts. Use a work email for work tools and a personal one for everything else.
7. Assuming every chat is private and ephemeral
Not all chats are deleted immediately. For example, Gemini keeps chat activity for 18 months by default, and any chats reviewed by humans are kept for up to three years (Gemini Apps Privacy Hub). Fix: Use “Temporary Chat” modes when available (like in ChatGPT), or check each tool’s data retention policy. For truly private chats, use a local model.
Which Chatbots Are Actually Private?
Privacy varies a lot by tool. ChatGPT and Claude let you stop training and offer Temporary Chat or Incognito modes; Gemini keeps activity for 18 months by default but lets you shorten it; Perplexity offers opt-outs on paid plans; Ollama runs fully offline. Here’s the quick comparison:
| Tool | Built-in privacy feature | Who it’s for |
|---|---|---|
| ChatGPT | Data Controls toggle + Temporary Chats: 30-day deletion, no training; Enterprise: no training on business data (OpenAI Data Controls FAQ, OpenAI Enterprise Privacy) | Casual users & businesses (with Enterprise). |
| Claude | Consumer Model Improvement opt-in; Incognito chats never used for training; Claude for Work no training by default (Anthropic Consumer Privacy, Anthropic Commercial Privacy) | Users who want a strong default privacy stance. |
| Gemini | Activity auto-delete (18-month default, adjustable); human-reviewed chats kept up to 3 years (Gemini Apps Privacy Hub) | Google ecosystem users who manage their activity settings. |
| Perplexity | Free standard; Pro/Max opt-out AI training; Enterprise data never used for training (Perplexity Plans) | Researchers needing up-to-date answers, with privacy tiers. |
| Ollama | Free, open-source, runs fully offline; data never leaves your machine, never trained on (ollama.com, Ollama pricing) | The ultimate privacy choice: tech-savvy beginners wanting full control. |
See our detailed tool comparisons for more.
Free vs. Paid: Does Paying Buy Privacy?
Not automatically. ChatGPT Plus and Claude Pro both cost $20/month and add speed and features, but paying alone doesn’t make your chats private. ChatGPT still trains on your data unless you turn off “Improve the model for everyone” (OpenAI Data Controls FAQ); Claude Pro only trains if you opt in to Model Improvement (Anthropic Consumer Privacy).
The real “privacy switch” is two-fold. First, you can often pay for a Business or Enterprise tier (like Claude for Work or ChatGPT Enterprise), which includes contractual guarantees that your data is not used for training and has stronger security (OpenAI Enterprise Privacy, Anthropic Commercial Privacy). Second, you can use local tools like Ollama, which is free and runs entirely on your own computer, meaning your data never leaves your control (Ollama).
Frequently Asked Questions
Quick answers to the questions beginners ask most about chatbot privacy. Each answer is based on the provider’s own documentation, verified in August 2026. If you’re in a hurry, the golden rule is simple: treat every chat as if it could be read, and never paste anything you wouldn’t post publicly.
Does ChatGPT train on my chats?
Only if the setting “Improve the model for everyone” is enabled. You can turn this off in Settings > Data Controls. When you use Temporary Chats, they are deleted after 30 days, are never used for training, and do not save to your chat history (OpenAI Data Controls FAQ).
Is it safe to paste a contract into Claude?
For the consumer version, it is generally safe because training is opt-in. Claude only trains on your data if you enable the “Model Improvement” option; Incognito chats are never used for training (Anthropic Consumer Privacy). Claude for Work and API users have even stronger defaults.
What should I never type into a chatbot?
You should never type real passwords, API keys, bank or credit card numbers, Social Security Numbers, or unreleased work data. Redact this information or use a local model like Ollama for handling truly sensitive queries, as recommended by security guidelines (OWASP).
What to Do Next
Start with the fix that takes two minutes, then build from there. These five steps turn this post into action, and each one links to a deeper resource when you’re ready. Bookmark this section and work through it the next time you open a chatbot.
- Toggle off training today. Visit the Data Controls or Privacy settings in every chatbot you use and disable data sharing for model training.
- Bookmark the privacy table above. Return to it whenever you choose a tool for a sensitive task.
- Read our Prompt Injection Prevention Guide to learn how to spot and avoid hidden instructions in text you paste.
- Try Ollama locally for truly private chats. Follow our step-by-step beginner’s guide to set it up on your machine.
- Adopt the golden rule: Before pasting, ask “Would I post this on Twitter?” If the answer is no, don’t paste it.
This post came from our content pipeline — see what’s scheduled next at /cron-pipeline/. Learn more about AI tool security in our comprehensive roadmap.
📖 Related Reads
- ToolBrain — tool reviews, LLM comparisons, and AI workflow guides
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