Folio PDF
Free document opener for Android — PDF, Word, Sheets, Slides, and Markdown in one app.
Open Utility.
Each tool solves one specific problem. They open immediately, run locally, and stay engineered to the same baseline as our paid software.
Open in browser.
Each utility runs in the browser. No install, no signup, no telemetry.
Direct Instruments.
No onboarding flow. No heavy client bundle. No conversion funnel hidden inside a free utility.
Dark pair readability
Check foreground and background pairs against readable contrast without leaving the page.
Preview surface
The pair should remain calm, warm, and easy to read on matte black.
14.12:1
Copy density check
Measure line length and paragraph density against the editorial ranges used across the site.
51Longest line
2Paragraph lines
101Total characters
Outside target
Launch width matrix
Keep the production QA widths visible while checking the current viewport against the launch set.
0px
320pxLaunch check
375pxLaunch check
390pxLaunch check
414pxLaunch check
768pxLaunch check
820pxLaunch check
1024pxLaunch check
1280pxLaunch check
1440pxLaunch check
1728pxLaunch check
1920pxLaunch check