AI Form Filling vs Browser Autofill: I Tested Both on 100 Real Websites

The argument that started a spreadsheet

A coworker told me browser autofill is "good enough for everything." I told him it puts my zip code in the phone field half the time. We went back and forth for ten minutes before I said something I immediately regretted: "Fine. I will test both on 100 websites and we will settle this with data."

That was three weekends ago. I have now visited 100 websites, filled every form twice (once with Chrome autofill, once with an AI form filler), and logged the results in a spreadsheet that has become an unhealthy obsession.

My coworker was wrong. But not as wrong as I expected. The real story is more interesting than a simple blowout.

The problem with browser autofill in 2026

Chrome's autofill was built for a different web. Back in 2011, most forms were plain HTML with predictable field names like first_name and phone_number. Chrome reads those HTML attributes and matches them against your saved data. Simple pattern matching.

The web moved on. Most sites now use React, Vue, or Angular. These frameworks generate field names dynamically. A phone field might be called input_8f3k2x in the HTML. Chrome looks at that and shrugs.

Then there are the forms that load in stages. Multi-step wizards where page 2 does not exist when Chrome runs its autofill on page load. Conditional fields that appear after you select an option. Custom dropdowns built with <div> elements instead of native <select> tags. Chrome cannot interact with any of them.

I wanted to know exactly how big the gap is. Not anecdotes. Numbers.

The test: 100 websites, two tools, one scoring system

I picked 100 real websites across 5 categories with 20 sites each:

1. E-commerce (Amazon, Target, Shopify stores, Zara, Nike, and 15 others)
2. Job portals (Greenhouse, Lever, Workday, LinkedIn, Indeed, and 15 others)
3. Government forms (IRS, state DMV portals, permit applications, benefits sites, and 16 others)
4. Travel (airlines, hotel chains, rental car agencies, booking aggregators, and 16 others)
5. SaaS signups (project management, CRM, analytics, dev tools, and 16 others)

For each site, I filled the form with Chrome autofill first, then cleared it and filled it again using Filliny. I scored each attempt as either a full success (every field correct, no manual corrections) or a failure (any field wrong, missing, or requiring manual intervention).

No partial credit. Either it worked perfectly or it did not. The real world does not give partial credit when your zip code is in the phone field.

The results: 42% vs 94%

Overall results across all 100 websites:

• Chrome autofill full success rate: 42 out of 100 (42%)
• AI form filling (Filliny) full success rate: 94 out of 100 (94%)
• Gap: 52 percentage points

But the averages hide the real story. The category breakdown is where things get interesting.

E-commerce (20 sites)

• Chrome autofill: 13 out of 20 (65%)
• AI form filling: 19 out of 20 (95%)

This was Chrome's best category. Major stores like Amazon and Target have well-coded forms that follow HTML standards. Chrome handles these fine. The failures came from Shopify custom themes, boutique stores with non-standard checkout flows, and one site that used a custom address autocomplete widget Chrome could not interact with.

Job portals (20 sites)

• Chrome autofill: 4 out of 20 (20%)
• AI form filling: 18 out of 20 (90%)

This is where Chrome falls apart. Workday, Greenhouse, and Lever all use multi-step forms with dynamic fields. Chrome fills page 1, partially. Pages 2 through 5? Nothing. The AI handled all the steps, including conditional fields like "Do you require sponsorship?" that trigger additional inputs.

Government forms (20 sites)

• Chrome autofill: 3 out of 20 (15%)
• AI form filling: 18 out of 20 (90%)

Chrome's worst category. Government sites use ancient custom components, non-standard date pickers, and field names like txtField_42 that give Chrome zero context. The AI reads the visible label "Social Security Number" or "Federal EIN" regardless of what the HTML calls the field. Two AI failures were on forms with CAPTCHA-gated sections that blocked automated interaction entirely.

Travel (20 sites)

• Chrome autofill: 10 out of 20 (50%)
• AI form filling: 19 out of 20 (95%)

Travel sites are a mixed bag. Major airline booking pages are well-built and Chrome handles the basic passenger fields. But the moment you hit a custom date picker, a country-code dropdown for phone numbers, or a frequent flyer number field, Chrome stalls. The single AI failure was a site with an embedded iframe for passport details that blocked external extension access.

SaaS signups (20 sites)

• Chrome autofill: 12 out of 20 (60%)
• AI form filling: 20 out of 20 (100%)

SaaS signup forms are usually short (5 to 10 fields) and Chrome handles the simple ones. But many ask contextual questions like "What is your role?" or "How large is your team?" in custom dropdown menus that Chrome ignores. The AI filled every single one including the open-ended "Tell us about your use case" text areas.

Speed comparison: faster is not always better

I also timed both tools on every form. The raw speed numbers favor Chrome:

• Chrome autofill average fill time (when it works): ~0.5 seconds
• AI form filling average fill time: ~2 seconds
• Speed difference: Chrome is about 1.5 seconds faster per form

Sounds like Chrome wins on speed. But here is the catch: when Chrome fails, you spend 3 to 5 minutes manually correcting the mess or typing everything from scratch. That 0.5-second fill becomes a 4-minute disaster.

Here is the real math. For 100 forms:

• Chrome: 42 successes at 0.5s + 58 failures at ~4 min manual = ~232 minutes total
• AI: 94 successes at 2s + 6 failures at ~4 min manual = ~27 minutes total
• Net time saved with AI: over 3 hours across 100 forms

Chrome is faster when it works. But it fails so often that the total time cost dwarfs the 1.5-second speed advantage. A tool that is 1.5 seconds slower but actually works is worth more than one that is instant and wrong.

Why the gap exists: HTML matching vs contextual AI

The 52-point gap is not a fluke. It comes from a fundamental difference in how the two approaches work.

How Chrome autofill works

• Reads HTML attributes: name, id, autocomplete on input elements
• Matches those attributes against a static dictionary of known field types
• Runs once on page load and ignores anything that appears after
• Can only interact with native HTML elements (<input>, <select>, <textarea>)

How AI form filling works

• Reads the visual layout, labels, placeholder text, and surrounding context
• Understands what each field is asking for regardless of the underlying HTML
• Observes the form as it changes, including new fields that appear dynamically
• Can interact with custom components, styled dropdowns, date pickers, and sliders

Think of it this way. Chrome autofill reads the code behind the form. AI form filling reads the form itself, the same way you do. When a government site labels a field "Federal Employer Identification Number" but the HTML calls it txtField_42, Chrome is lost. The AI reads the label and knows exactly what goes there.

Browser autofill asks the code what the field is. AI form filling asks the field what it is. That single difference explains the entire 52-point gap.

Being fair: where Chrome autofill still wins

I would not trust a review that only highlights one side. Chrome autofill has real advantages that matter:

• It is free. No subscription, no account, no setup. It is just there, built into every Chrome browser.
• It is fast. When it works, 0.5 seconds is nearly instant. No waiting for AI processing.
• It works offline. AI form filling requires an internet connection for the AI to process the form. Chrome autofill works without one.
• Simple forms are handled perfectly. A basic name-email-address form on a well-coded site? Chrome nails it 100% of the time.
• No third-party extension needed. Some people prefer not to install additional extensions regardless of what they do.

If every form you encounter is a simple address form on a major e-commerce site, Chrome autofill is genuinely all you need. Do not pay for something you do not need.

The gap only appears when you move beyond basic forms. Job applications, government sites, multi-step wizards, custom-styled inputs. That is where the 42% vs 94% difference lives.

What the 6 AI failures looked like

The AI was not perfect. 94 out of 100 means 6 failures. Here is exactly what went wrong:

1. Two government sites with CAPTCHA gates that blocked the extension from interacting with fields behind the verification step
2. One travel site with an embedded iframe for passport details that sandboxed the form away from extension access
3. One job portal with an ambiguous dropdown where the AI selected "Mr." for a field that wanted a professional title like "Software Engineer"
4. One e-commerce site with a custom address autocomplete widget that intercepted input before the AI could write to the field
5. One government form that used Flash-era ActiveX components. Yes, in 2026. No modern tool can interact with those.

Most of these failures are edge cases that no form-filling tool could handle. The ambiguous dropdown was the only failure I would call a genuine AI mistake. And it was easy to fix with a single click to change the selection.

What other testers found

I shared my spreadsheet methodology in a developer Slack group and three people replicated smaller versions of the test (25 to 40 sites each). Their results were consistent with mine:

• "Chrome got 11 out of 25 on my test. Filliny got 23. The job application sites were the biggest gap."
• "Tested 40 sites. Chrome 38%, AI 92%. The government forms were painful. Chrome did not fill a single state tax portal correctly."
• "My numbers: Chrome 48% on 30 sites, AI 93%. The e-commerce gap was smaller than I expected. The real difference shows on complex forms."

The pattern held. Chrome does well on simple, well-coded forms. The AI does well on everything.

The cost question

Chrome autofill is free. That matters. Any comparison needs to address whether the AI alternative is worth paying for.

Here is how I think about it:

• Each Chrome autofill failure costs 3 to 5 minutes of manual correction
• If you fill 20 forms per week, Chrome fails on roughly 12 of them (58% failure rate)
• That is 36 to 60 minutes per week lost to manual corrections
• At $25/hour, that is $15 to $25 per week in wasted time
• Filliny Pro plan: $12/month ($8.25/month on the annual plan)

"Free" sounds cheaper until you calculate what the failures actually cost you. The time tax on Chrome autofill failures adds up to more than the subscription in the first week.

Checklist: is AI form filling right for you?

Be honest with yourself. Not everyone needs this.

• You fill out more than 10 forms per week
• You regularly use job application portals (Workday, Greenhouse, Lever)
• You deal with government or institutional forms
• Chrome autofill regularly puts your data in the wrong fields
• You encounter multi-step forms or custom dropdown menus often
• You value your time at more than $3/hour
• You only fill out 1-2 simple forms per month on major websites
• Every form you encounter works perfectly with Chrome autofill
• You prefer not to install any browser extensions

If you checked 3 or more of the first six, the free tier alone will show you the difference. If all three bottom items describe you, Chrome autofill is genuinely fine.

A summary table for the skimmers

For those scrolling straight to the bottom, here is the entire comparison:

• Overall accuracy: Chrome 42% vs AI 94%
• E-commerce: Chrome 65% vs AI 95%
• Job portals: Chrome 20% vs AI 90%
• Government: Chrome 15% vs AI 90%
• Travel: Chrome 50% vs AI 95%
• SaaS signups: Chrome 60% vs AI 100%
• Fill speed (when working): Chrome ~0.5s vs AI ~2s
• Net time for 100 forms: Chrome ~232 min vs AI ~27 min
• Cost: Chrome free vs AI $12/month (5 free fills included)

The proposal: test it on your hardest form

I am not going to tell you to switch. The data speaks for itself. But here is what I would do if I were reading this and wondering whether it applies to me.

Think of the worst form you fill out regularly. The Workday application that takes 15 minutes. The government portal that Chrome refuses to touch. The travel booking with the custom date pickers. Whatever form makes you sigh before you start.

Filliny gives you 5 free form fills. No credit card. No commitment. Use one of them on that worst form. If the AI handles your hardest form, everything else will be easy.

1. Install Filliny from the Chrome Web Store (15 seconds)
2. Create a profile with your basic info (30 seconds)
3. Navigate to your most difficult form and click the Filliny icon
4. Watch it fill fields that Chrome autofill has never touched

My coworker tried it on a Workday application. He stopped arguing after that.

Chrome autofill is not a bad tool. It is just a tool built for a web that no longer exists. For simple forms on well-coded sites, it works fine. For everything else, the AI wins by a margin that is not even close.