The app doesn't matter. The alerts do. Every mobile portfolio tracker app with alerts promises you'll never miss a move, but the honest comparison isn't about the app at all.
Price alerts are table stakes and, frankly, mostly noise for a long-term ETF holder. The alerts that matter are rarer: allocation drift, dividend announcements, corporate actions on funds you hold. Start there and work backward to the app.
First question: one brokerage or three? If your money sprawls across accounts, a tracker that only sees one of them is a rumor, not a report. Some apps offer aggregation. Verify what it actually covers before assuming it sees everything. Second: alert customization. Can you set "tell me when my stock allocation passes 85%" or only "tell me when VOO moves 5%"? The first protects the plan. The second feeds the checking habit. There's also an alert worth wanting that nobody advertises: overlap warnings when a new fund duplicates what you hold. An ETF overlap analyzer app, iOS and Android both, handles that ten-second check.
The usual suspects are fine, honestly. Yahoo Finance does watchlists and alerts, and half the investing internet already has it. Your broker's app covers the accounts it can see. The best ETF comparison tool for the research behind the alerts is a separate question from the tracker itself. Don't expect one app to do both jobs well. Specialists beat generalists here.
My filter is brutal and simple: the best tracker is the one whose alerts you haven't muted after a month. Muted means it failed, no matter how pretty the charts. Fewer, smarter alerts beat a firehose. Set drift thresholds, set dividend reminders, kill the price noise, and let the phone stay in your pocket.
When an alert fires and something needs a second look, compare before you act. ETFCompare lines up 108 ETFs with fees, overlap, and returns side by side. Start at etfcompare.fyi.