Write your resume, pick a clean template, check it against a job posting and save it as a PDF with your browser's print dialog. The text stays real, selectable text, which applicant tracking systems can read. Your details never leave your device.
Design
About you
Experience
Education
Skills
Projects
Certifications and extras
Check against a job posting
Quick review
In the print dialog choose "Save as PDF", set margins to Default or None, and turn off "Headers and footers".
Your resume is saved in this browser as you type, and nowhere else. Download your data now and then as a backup. The keyword check and review are simple text matches, not a guarantee of how any employer's system will score you.