
Microsoft Office Excel
Google Sheets
DB Browser for SQLite
Modern CSV
LibreOffice
Airtable
Apache OpenOffice Calc
100% local, zero uploads. Process millions of rows entirely in your browser. The ultimate privacy-first toolkit for CSV, ecommerce, and marketing data.

StackMail
A self-hosted, unified webmail client. Connect multiple IMAP/SMTP accounts and manage them all in one clean interface.

Which is more popular?
Website, pricing, platforms and company facts side by side.
|
|
|
|
|---|---|---|
| Website | dataprep.dev | mailflow.sh |
| Pricing | ||
| Platforms | — | |
| Company | Startup from the United States · 1 - 9 employees · 2026 | — |
| Listed in |
In their own words, as submitted to SaaSHub.


The Browser Data Toolkit for Privacy-Conscious Professionals dataprep.dev is a 100% local, pure-browser data processing engine designed to solve the biggest headaches in data preparation: Excel crashes and privacy risks. Powered by cutting-edge DuckDB-Wasm technology, our toolkit brings...
No description of Mailflow.sh yet.
What each product offers, as listed by its team.


Possible disadvantages
Walkthroughs and reviews on video.
Instant SQL on CSV in Browser (DuckDB-Wasm) - Zero Uploads
No Mailflow.sh videos yet. You could help us improve this page by suggesting one.
How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing dataprep.dev and Mailflow.sh.
dataprep.dev's answer
I was trying to clean up a massive, messy Shopify order export. Excel kept freezing, and I absolutely refused to upload sensitive customer emails to random online converters. I got so frustrated that I decided to stop complaining and build a local-first toolkit to solve my own workflow nightmare.
dataprep.dev's answer
1, Indie hackers and solo founders. 2, Boutique digital marketing agencies. 3, Privacy-conscious data freelancers.
dataprep.dev's answer
Most data tools force you to upload your CSVs to their servers. We don't. We compiled DuckDB into WebAssembly, meaning you get a blazing-fast, database-level engine running entirely inside your local browser tab. It's 100% private and works instantly.
dataprep.dev's answer
If you try to open a 2GB CSV in Excel, it freezes and crashes. If you use Python Pandas, you have to write code and manage environments. dataprep.dev gives you the power of code (SQL queries, regex, merging 50 files) with a simple drag-and-drop UI, without ever freezing your computer.
dataprep.dev's answer
E-commerce sellers flattening messy Shopify exports, performance marketers cleaning ad reports, and data analysts who need to anonymize PII (GDPR compliance) before feeding datasets to AI models like ChatGPT.
dataprep.dev's answer
DuckDB-Wasm is the core data engine handling the heavy lifting. The frontend is built with React/Next.js and styled with Tailwind CSS. It's a modern, serverless architecture.
Share your experience with using dataprep.dev and Mailflow.sh. For example, how are they different and which one is better?
When comparing dataprep.dev and Mailflow.sh, you can also consider the following products.

Microsoft Office Excel is a commercial spreadsheet application.
Compare Microsoft Office Excel to dataprep.dev or Mailflow.sh:

Stackmail is a webmail service whereby you can log in to your emails from any browser at any time!
Compare StackMail to dataprep.dev or Mailflow.sh:

Synchronizing, online-based word processor, part of Google Drive.
Compare Google Sheets to dataprep.dev or Mailflow.sh:

News. 2017-09-28 - Added PortableApp version of 3. 10. 1. Thanks John.
Compare DB Browser for SQLite to dataprep.dev or Mailflow.sh:


Free office suite, open source, and compatible with .doc, .docx, .xls, .xlsx, .ppt, .pptx files. Updated regularly – download for free. Originally based on OpenOffice.org.
Compare LibreOffice to dataprep.dev or Mailflow.sh: