Side by side
Grackle GO vs Horn
Both stand on accessibility testing software. Which one you can start free with, which one lets you read the code, and what each costs once you pay.
Free plan WebWindowsMac+1
Choose Grackle GO for automated PDF checks with tagging, reading order, alternative-text, and remediation tools on a free plan. Look elsewhere if your workflow requires manual review, mobile testing, a browser extension, or CI/CD integration.
Visit Grackle GO
Free plan APIExtensionLinux+4
Horn offers broad PDF accessibility checking with command-line, desktop, browser, and CI delivery options. Its manual-review conditions mean results should be followed by human assessment.
Visit HornThe facts
| Grackle GO | Horn | |
|---|---|---|
| Free plan | Yes | Yes |
| Open source | Not published | Not published |
| Runs on | Web, Windows, Mac, Linux | API, Extension, Linux, Mac, Self-hosted, Web, Windows |
| Lowest paid plan | Free or on request | Not published |
| Plans published | 1 | None |
| Maker | Grackle GO | Not published |
| Website | grackledocs.com | github.com |
| On accessibility testing software | #65 of 169 | #61 of 169 |
Grackle GO: what it does well
- Automated scans for PDF accessibility.
- Includes PDF tagging, reading order, and alternative-text tools.
- Provides remediation guidance.
- Supports PDF/UA and OCR.
- Available on web, Windows, macOS, and Linux.
What to know first
- Unauthenticated users are limited to 10 validations per hour.
- Files are limited to 25 MB on the Free plan.
- No manual review tools or mobile testing.
- No browser extension or CI/CD integration.
Horn: what it does well
- Validates PDF/UA-1 and PDF/UA-2
- Automates 87 Matterhorn conditions
- Multiple CLI, desktop, web, and CI options
- SARIF and JUnit XML outputs
- Zero runtime dependencies
What to know first
- 48 conditions still require human judgment
- Two conditions have no defined test
- Automated scans are not a complete assessment
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