I built free data conversion & utilties tools that run entirely in your browser
Every time I needed to quickly convert a JSON file to CSV or clean duplicates from an Excel sheet, I'd land on some sketchy site asking me to upload my file to their server. For personal projects that's annoying. For work data, it's a hard no.
So I built DataFrog (datafrog.tools) — a collection of free, browser-based data conversion and utilties tools where your data never leaves your device. Ever.
What it does:
Everything runs client-side in JavaScript. No uploads, no accounts, no usage limits. Works offline after the first visit too.
Tools cover pretty much every format combo developers and analysts actually run into:
JSON ↔ CSV, Excel, XML, YAML, SQL, TypeScript, Dart, Go, C#, Java
Excel ↔ JSON, CSV, HTML, SQL, PDF
CSV ↔ JSON, XML, SQL, HTML
QIF → CSV / Excel / QBO (for finance folks)
Duplicate removal, UUID generator, Base64, Hash generator, and more
Who it's for:
Developers inspecting API responses, analysts preparing data for imports, finance teams dealing with QIF bank exports, DevOps engineers wrangling YAML configs, and anyone who's pasted data into a dodgy online converter and immediately regretted it.
The "why" behind it:
Privacy is the actual feature here, not a checkbox in the footer. When you're converting a production database export or a client's financial file, you shouldn't have to trust a random server you've never heard of.
Where it stands:
Free, fully functional, and getting new converters added regularly. No monetization yet — currently just focused on building something genuinely useful and getting it in front of people who need it.
Would love feedback from anyone who works with data day-to-day. What converter is missing that you wish existed?
If you have seen my site or willing to visit, please visit and let me know if you want me to add the tools are missing or adding new features I am missing in any tool.
Regards
That “random converter for client files” pain is very real. The privacy feature here is not just “we don’t store uploads,” it’s that there is no upload path in the normal workflow at all.
I’d probably make that brutally obvious before the tool list: open file, convert locally, close tab, nothing sent. That is the thing a cautious developer or ops person can understand in two seconds.
We think about the same trust problem with email: the best privacy claim is the one the product shape makes hard to violate.
The strongest part here is not the number of converters.
It is the trust angle: “useful data tools for files you cannot risk uploading anywhere.”
That is much sharper than competing as another free utility site.
I’d be careful not to keep expanding only by adding more tools. The bigger question is which user has the highest trust pain: developers with production exports, analysts handling client data, or finance teams working with bank files.
That probably matters more than the next converter.