GlockApps vs Email on Acid by Sinch
Side-by-side from the Top 11 ranking of The 11 Best Email Deliverability Tools. Last verified June 15, 2026.
The short answer
GlockApps ranks higher on Top 11 (#1 vs #6) for Email marketers and developers improving inbox placement rates. Top-tier inbox placement testing with a broad, international seed list and actionable reports.
At a glance
| GlockApps | Email on Acid by Sinch | |
|---|---|---|
| Top 11 rank | #1 / The 11 Best Email Deliverability Tools | #6 / The 11 Best Email Deliverability Tools |
| Score (out of 9.4) | 9.2 | 8.1 |
| Best for | Detailed inbox placement testing | Pre-send testing workflow |
| Pricing | $$ ($79 to $399/mo) | $$ ($99 to $599/mo) |
| HQ | Hong Kong | Denver, USA |
| Founded | 2011 | 2009 |
GlockApps
Top-tier inbox placement testing with a broad, international seed list and actionable reports.
glockapps.com/Email on Acid by Sinch
Combines elite email rendering previews with capable deliverability and blocklist monitoring.
www.emailonacid.com/Methodology and scoring weights live at /methodology. No vendor pays for placement — see about.