u/Universalboys

I'm working on an idea and wanted honest feedback from people who've actually gone through the N-400 process.

One thing I keep seeing is that people struggle with:

calculating physical presence correctly

organizing large travel histories

figuring out the 90-day early filing date

formatting I-94 travel history

My idea is to build a browser-based tool that runs completely on your device (no login, no uploads, no data stored) to make those parts easier.

Would something like this actually be useful, or is there another part of the N-400 process that's even more frustrating?

I'm genuinely looking for feedback before spending more time building it.

I'm curious what Excel task people still spend way too much time on.

Not formulas or dashboards.

I mean repetitive tasks where you think:

"There should be a simple tool for this."

What are you comparing, matching, cleaning, reconciling, or checking manually over and over? Any

A real example would be helpful.

What spreadsheet or CSV task do you wish had a dead-simple tool?

Trying to understand where teams still waste hours every week.

What's the most frustrating thing you compare in Excel or CSV files on a regular basis?

Email lists?

Inventory?

Invoices?

Something else?

Trying to figure out what tool to build next and add to my website.

I kept running into the same problem at work and on side projects.

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I'd export data from two different systems and then spend way too much time figuring out:

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- Which records exist only in File A

- Which exist only in File B

- Which records match

- Whether I accidentally introduced duplicates

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Most solutions I found either required uploads, accounts, or felt overkill for a simple comparison task.

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So over the last few weeks I built a browser-based tool that compares lists and Excel columns locally on your device.

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Some things I focused on:

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• Excel column comparison

• Same workbook or different workbooks

• Large datasets handled with Web Workers

• No login

• No server processing

• CSV/TXT exports

• Difference, Match, and Combined views

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The hardest part was surprisingly Excel compatibility. Things like hidden rows, dates, currency formatting, duplicate detection, and getting uploaded spreadsheets to behave exactly like copied spreadsheet data took much longer than expected.

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I'm curious:

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What's the most annoying spreadsheet comparison task you've had to do manually?

I regularly work with spreadsheet exports and large text datasets, and most comparison tools I found either uploaded data to servers or struggled with large inputs.

So I built a browser-based utility focused on:

- local processing

- privacy

- fast comparisons

- duplicate detection

- dataset cleanup

Interesting engineering challenges were:

- deterministic deduplication

- preserving first-seen casing during ignore-case matching

- handling invisible unicode characters

- keeping UI responsive with Web Workers

Still improving the UX and parser behavior, but happy with the current direction so far.