American Express vs. Zynlo Bank
High-Yield Savings Account Comparison
By Aviel Fahl|Last Updated: October 21, 2025
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Summary of American Express vs. Zynlo Bank
Key Metrics at a Glance
| Feature | American Express | Zynlo Bank |
|---|---|---|
| Top Savings APY | 3.50% High Yield Savings Account | 4.20% Tomorrow Savings Account |
| Minimum to Open | $0 | $10 |
| Minimum Balance for Top APY | $0 | $0.01 |
American Express
Strengths
- American Express offers a competitive APY of 3.50%.
- No maintenance fees or minimum balance requirements for the High Yield Savings Account.
- High App Store rating of 4.9.
Potential Drawbacks
- American Express has a BBB rating of F and is not accredited.
- No branches available for in-person banking.
- Google Play rating is only 3.7.
Zynlo Bank
Strengths
- Zynlo Bank offers a higher APY of 4.20%, though it decreased from 4.35%.
- BBB rating of A+, indicating better trustworthiness.
- No maintenance fees or minimum balance requirements for the Tomorrow Savings Account.
Potential Drawbacks
- Zynlo Bank has a lower App Store rating of 4.0.
- No branches available for in-person banking.
- Google Play rating is only 3.5.
→ As of October 21, 2025 American Express offers an APY of 3.50% for its High Yield Savings Account, with a minimum balance of $0, compared to Zynlo Bank's 4.20% APY for its Tomorrow Savings Account, with a minimum balance of $0.01.
→ Zynlo Bank yields $70 more than American Express on a $10,000 balance after one year. American Express pays $350, while Zynlo Bank pays $420 - an APY advantage for Zynlo Bank.
Calculate Savings Growth for American Express vs Zynlo Bank
American Express - High Yield Savings Account
Total savings breakdown:
- Interest earned: $2,114.1 (10.51%)
- Total contributions: $13,000 (64.63%)
- Initial deposit: $5,000 (24.86%)
Your total balance
$20,114.10
Total balance: $20,114.1
Earnings: $2,114.1
Bank OverviewZynlo Bank - Tomorrow Savings Account
Total savings breakdown:
- Interest earned: $2,564.3 (12.47%)
- Total contributions: $13,000 (63.22%)
- Initial deposit: $5,000 (24.31%)
Your total balance
$20,564.30
Total balance: $20,564.3
Earnings: $2,564.3
Bank OverviewWith a $5,000 initial deposit and $13,000 in total contributions over 5 years, American Express's total earnings would be $450.2 lower than Zynlo Bank's total earnings.
The Banksparency Savings Calculator provides estimated savings growth based on user input and our latest data.
Compare American Express' vs Zynlo Bank's Savings Accounts
| American Express | Zynlo Bank | ||
|---|---|---|---|
| Product | High Yield Savings Account | vs | Tomorrow Savings Account |
| APY | 3.50% (as of 10/21/2025) | 4.20% (as of 10/21/2025) | |
| Bundled Account | No | No | |
| FDIC-insured | Yes | Yes | |
| Online Only | Yes | Yes | |
| Compound Frequency | Daily | Daily | |
| Minimum Deposit | $0 | $10 | |
| Minimum Balance for APY | $0 | $0.01 | |
| Maintenance Fee | $0 | $0 | |
| Direct Deposit Required | No | No | |
| App Store Rating | 4.9/5 | 4.0/5 | |
| Google Play Rating | 3.7/5 | 3.5/5 | |
| BBB Rating | F | A+ |
Comparative Historical APY Insights (Last 7 Months)
| American Express | Zynlo Bank | ||
|---|---|---|---|
| Product | High Yield Savings Account | vs | Tomorrow Savings Account |
| Latest APY | 3.50 % | 4.20 % | |
| Trend | Sideways | Sideways | |
| Slope (bps/mo) | -3.5 | -0.7 | |
| Rate Changes / Mo | 0.27 | 0.14 | |
| Days Since Last Change | 90 | 12 | |
| High (-7 m) | 3.70 % | 4.35 % | |
| Low (-7 m) | 3.50 % | 4.20 % | |
| Draw-down from High | -5.4 % | -3.4 % | |
| Volatility (CV) | 0.022 | 0.008 |
APY Insights Glossary
- Latest APY
- Most recent advertised annual-percentage yield.
- Trend
- Direction over the last 7 months (regression slope).
- Slope (bps/mo)
- Average monthly change; 10 bps = 0.10 pp.
- Rate Changes / Mo
- Typical number of APY moves per month.
- Days Since Last Change
- Recency of the latest APY adjustment.
- High (-7 m)
- Highest APY in the last 219 days.
- Low (-7 m)
- Lowest APY in the last 219 days.
- Draw-down from High
- How far today sits below the 7-month peak.
- Volatility (CV)
- Coefficient of variation = stdev ÷ mean.
Why Track Savings-Account APYs?
- See how quickly a bank reacts to Fed moves or competition.
- Gauge “twitchiness” - frequent moves can annoy savers.
- Spot if you're buying near a peak (draw-down) or riding a rise.
- Slope (bps/mo) shows speed of change.
- Volatility (CV) scales jumps by average level.