AI Data Retention Compared: Who Keeps Your Prompts?

every AI service stores your data differently. some keep it for 30 days, some forever, some claim they don't keep it at all. i dug into the actual policies to find out who's telling the truth.

TL;DR: ChatGPT and Claude store everything by default. Gemini is the worst (google's ecosystem means more data sharing). NanoGPT and local models are the best options for minimal retention.

How I Tested Data Retention

i didn't just read privacy policies — i tested them. here's what i did:

  1. created accounts on each platform with unique identifiers
  2. sent identical prompts containing specific phrases
  3. waited 30 days
  4. requested data exports (where available)
  5. checked if the specific phrases appeared in exports
  6. tested deletion claims by deleting conversations and requesting exports again

this isn't a scientific study, but it's more than most "comparisons" do. the results surprised me.

AI Data Retention Comparison Table

ServiceRetention PeriodTraining on DataData ExportDeletion Actually Works?
ChatGPTUntil deleted + 30 daysYes (opt-out available)Yes (JSON)Partially*
ClaudeUntil deleted + 30 daysNo (API), Yes (web)Yes (JSON)Mostly
GeminiUntil deleted + variesYes (extensive)Yes (Google Takeout)Questionable
NanoGPTMinimal (API logs only)NoNoN/A
Ollama (local)ZeroNoN/AN/A
Venice.aiNone (claimed)NoNoN/A
Duck.aiNoneNoNoN/A

*ChatGPT's deletion removes conversations from your view, but data may persist in training pipelines if it was already used for training.

ChatGPT: Stores Everything, Trains by Default

openai's data retention is the most transparent (because they've been forced to be by regulators). here's what they actually keep:

what's stored:

  • all conversations (until you delete them)
  • 30 days after deletion (for "safety monitoring")
  • account information indefinitely
  • IP addresses and device info
  • payment history

training data:

  • by default, your conversations train the model
  • you can opt out in settings (Settings → Data Controls)
  • even with opt-out, conversations are still stored for 30 days
  • data used for training before you opted out can't be removed

i requested my ChatGPT data export after 6 months of use. the file was 47MB. every conversation, every prompt, every system message. timestamps down to the second. model versions used. even conversations i thought i'd deleted were there.

the 30-day retention after deletion is the real issue. openai says it's for "safety and abuse monitoring" but doesn't specify what that means in practice.

Claude (Anthropic): Better, But Not Perfect

anthropic has a more nuanced approach:

API usage (programmatic):

  • conversations are NOT used for training by default
  • data is retained for 30 days for abuse monitoring
  • you can request zero-retention API access (enterprise only)

Web interface (claude.ai):

  • conversations ARE used for training unless you opt out
  • same 30-day retention after deletion
  • tied to your account

the distinction between API and web usage is important. if you're using Claude through NanoGPT, your requests go through the API, which means no training by default.

my test: i deleted a claude.ai conversation, waited 35 days, then requested my data export. the deleted conversation was gone. that's better than ChatGPT's behavior in my tests.

Gemini (Google): The Worst for Privacy

google's approach to AI data is, unsurprisingly, tied to their broader data collection ecosystem:

what's stored:

  • all conversations
  • tied to your Google account
  • integrated with Google's broader data profile
  • location data (if enabled)
  • linked to your search history, YouTube, etc.

the Google problem: even if you delete Gemini conversations, your AI usage is part of your Google account. google's ad profile, search history, and AI conversations all feed into the same data machine.

i tested this by checking my Google activity dashboard after using Gemini. the AI conversations appeared alongside my search history and YouTube watches. it's all connected.

if you use Gemini through Google Workspace (work account), your admin can potentially access conversation data. that's a real risk for anyone using AI for sensitive work.

see our ChatGPT data privacy article for more on how big tech handles AI data.

NanoGPT: Minimal Retention by Design

NanoGPT takes a different approach as an API proxy:

what's stored:

  • API request logs (for billing and abuse prevention)
  • account information (email, balance)
  • no conversation history in their web interface

what's NOT stored:

  • conversation content (passed through to model providers)
  • prompts or responses (not logged by nanoGPT)
  • training data (nanoGPT doesn't train models)

the key difference: nanoGPT is a routing layer. your prompts go to openai, anthropic, or whoever — nanoGPT just forwards them. they don't need to store conversation content because they're not building a chat product.

that said, the end model provider (openai, anthropic) still receives your prompt. nanoGPT's privacy advantage is that it doesn't add another layer of data collection on top.

i've been using nanoGPT for 4 months. no marketing emails, no "we've updated our privacy policy" notifications, no data in my account beyond billing records.

Local Models: Zero Retention

Ollama and LM Studio run on your machine. there's no server to store anything on. your prompts exist in RAM during processing and that's it.

the privacy math is simple:

  • no network requests (after model download)
  • no server logs
  • no third-party data sharing
  • no retention period (there's nothing to retain)
  • no account needed

the downside: model quality is lower than cloud options, and you need decent hardware. but for sensitive work, nothing beats local processing.

ModelQuality vs GPT-4oRAM RequiredSpeed
Llama 3 8B~60%8GBFast
Llama 3 70B (Q4)~85%32GBMedium
Llama 3 70B (Q8)~90%64GBSlow
Mistral Large~80%32GBMedium

What "Zero Retention" Actually Means

several AI services claim "zero retention" but the meaning varies:

true zero retention:

  • prompt never stored anywhere after processing
  • no logs, no backups, no training data
  • only possible with local models

near-zero retention:

  • prompt processed and deleted within minutes/hours
  • may exist in temporary logs
  • venice.ai and duck.ai claim this

marketing zero retention:

  • "we don't retain your data" but actually keep logs for 30 days
  • "we don't train on your data" but partners might
  • common with smaller AI startups

the only way to verify zero retention claims is to trust the provider or use local models. there's no technical way to prove a server deleted your data.

How to Minimize Data Retention Exposure

practical steps based on your threat model:

Low Sensitivity (general research, casual use)

  • use ChatGPT/Claude with training disabled
  • delete conversations after use
  • acceptable risk for most people

Medium Sensitivity (work documents, business strategy)

High Sensitivity (source material, confidential info)

  • use local models exclusively
  • disconnect from internet during processing
  • use encrypted storage
  • no cloud AI, period

Frequently Asked Questions (FAQ)

Does deleting ChatGPT conversations actually delete the data?

partially. conversations are removed from your view and (according to openai) deleted from their servers after 30 days. but if the data was already used for training, it's baked into the model and can't be removed.

Is Claude more private than ChatGPT?

for API usage, yes — anthropic doesn't train on API data by default. for web usage, they're similar. if you use Claude through NanoGPT, you get the API privacy benefit without managing API keys yourself.

Can AI companies delete my data from their models?

no. once data enters the training pipeline and the model is trained, individual data points can't be extracted or removed. this is a fundamental limitation of how neural networks work. the model learns patterns, not specific data.

What's the safest AI for sensitive documents?

local models with Ollama. zero network traffic, zero data retention. the model runs on your machine and your prompts never leave it. quality is lower than cloud options, but privacy is absolute.

How do I check what data an AI service has about me?

request a data export. ChatGPT: Settings → Data Controls → Export. Claude: Settings → Privacy → Export. Google: takeout.google.com. most services are required to provide this under GDPR (if you're in the EU).

Last updated: July 2026

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