oh man, I feel u. That $20 subscription adds up soooo fast when youre just trying to get some quick charts done. In my experience, I've tried many free tools cuz I hate paying for stuff if I dont have to lol. Honestly, I'm still kinda a beginner at the heavy data stuff but I've found a few options that lowkey do exactly what ChatGPT Plus does without the cost. I remember being soooo frustrated trying to make a simple scatter plot in a spreadsheet last month, and one of these tools just did it in two seconds for me. It felt like magic! For your situation, here is what I recommend:

• Claude 3.5 Sonnet on the free tier. This is highkey the best one right now. It has a built-in analysis tool that runs code to process your CSV and can even show charts in a window on the side. The downside is you only get a few messages every few hours, so if your files are huge, you gotta be efficient.
• Google Gemini. This one is pretty great because the limits are way higher. It can handle file uploads and write Python scripts to visualize everything. Plus, it links right into Google Sheets which is handy if you use that already. It might be slightly less smart than others, but it gets the job done.
• Julius AI. This is a specialized data tool. It's reallyyy good at automatically making pretty charts without needing complex prompts. You get about 15 messages a month for free, which might be enough if you just have a couple files? Honestly, Claude 3.5 Sonnet is the smartest, but Google Gemini is more reliable if you have a lot of work to do. I'd start with Claude and see how it goes... gl!

Respectfully, I'd consider another option before you get too deep into the web-based AI tools. I mean, they're cool, but when you're dealing with actually large CSV files, you gotta be careful. Most free tiers for cloud tools have strict row limits or token caps, so they might choke if the file is truly huge... it's a major buzzkill when you're halfway through. I would suggest trying KNIME Analytics Platform instead. It's open-source and totally free, and since it runs locally on your machine, it handles massive datasets way better than a browser-based AI. It uses a visual drag-and-drop interface so you don't really have to code, which is nice... kinda like a pro version of a spreadsheet for data cleaning. Also, honestly, Microsoft Power BI Desktop is a literal life-saver for visualization. It's free to download and handles big data like a pro. I've used it for files with massive row counts where ChatGPT would just stall out. Just make sure to check some tutorials first cuz the interface is a bit much at first. gl!

Yo, in my experience, Claude 3.5 Sonnet is actually the best free bet for analyzing big CSVs cuz it handles complex logic like a pro.

• Use Claude 3.5 Sonnet for heavy data cleaning and prep.
• Try Julius AI if you wanna generate charts fast without any coding... its super easy. Youll basically get that Plus experience for free with these two!

Late to the party but honestly if you want reliability for free, I would go with a combo of DeepSeek-V2 and Google Colab. Most free AI chat tools have tiny limits on file size or the number of rows they will actually look at. Instead, just ask the free version of DeepSeek-V2 to write a Python script for your specific analysis. Then, upload your CSV to Google Colab and run the code there. It is totally free, handles massive files easily, and gives you high-res charts. If you want something more like an all-in-one app, check out Mistral Le Chat. It is surprisingly good at handling logic and data tasks for a free tool. Also, Tableau Public Desktop is amazing for the visualization side of things if you dont mind your data being saved to their public gallery. It is way more powerful than any AI chart generator tbh.

Like someone mentioned, these web tools can be a bit of a letdown. Honestly, I have had issues with how some of these free platforms handle data privacy... it is not as good as expected when you realize your files might be sitting on some random server. Kinda disappointing tbh. I am gonna have to disagree with just jumping into every free AI site mentioned here tho. You really gotta be cautious about your data security. If you want the real tea on what works safely:

• Search on Reddit for data privacy AI threads. There are tons of people who have already compared all the big brands in those communities.
• Check YouTube for comparison videos on secure local data analysis. I saw a really good one about this recently that explained the risks.
• Honestly just look at the documentation on official developer sites for open source tools. They usually have guides that are way more reliable than random forums. Its definitely tricky to find a good balance of free and safe... good luck with the search.