gs-batch-pdf vs yq

gs-batch-pdf is a free, MIT-licensed command-line tool for processing PDF files in parallel on Windows, Linux, and macOS. It applies Ghostscript presets including /screen, /ebook, /printer, /prepress, and /default, and converts files to PDF/A-1, PDF/A-2, or PDF/A-3. Correct PDF/A-2 and PDF/A-3 conversion requires Ghostscript 10.04.0 or newer. Recursive directory processing can report progress for each file. You can keep the smaller result or always keep the newly processed file, add filename prefixes or suffixes, and choose whether failures prompt, skip, or abort. Silent options support unattended runs, including forced overwrites, suppressed output-folder opening, and skipped errors. Arbitrary Ghostscript options are accepted. Python 3.12 or later and a separately installed Ghostscript executable are required; pipx is recommended, while pip is also supported. No API access is listed.

yq has no write-up on Specifiction yet; its figures are above.