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Chaekgalpi Tools › Books & PDF
TrimPDF
Trims the wide margins of a scanned book PDF and enlarges the text so it reads comfortably on a tablet or e-reader.
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Windows program · AGPL-3.0 · v1.0.2 · Updated 2026-10-14
For Windows. The file is unsigned, so if "Windows protected your PC" appears the first time, choose "More info → Run anyway".
Chaekgalpi Tools are made by the person who runs Chaekgalpi Library, a Korean-language web service for keeping a reading log. About Chaekgalpi Library (Korean) →
How to use
- Download TrimPDF.exe and run it (no install).
- Drop PDF files onto the window. Several files at once is fine.
filename_TrimPDF.pdfis created in the same folder. The original is untouched.
Features
- Pages are not turned into images, so text selection, search and the table of contents are kept.
- Yellowed backgrounds, dust and edge shadows are ignored; only the real content area is detected.
- Files are processed on your PC only and never uploaded.
- Interface in Korean, English and Chinese.
What it does not do
- Links, notes and form fields in the original are not carried over to the result.
- Password-protected PDFs are not processed.
Since v1.0.3, the program sends only its name and version to the Chaekgalpi server when it starts, to check whether a newer version exists. No file is sent, it asks once a day, and you can turn it off in the settings.
Other tools in this group
- Two-page Split (Windows) — Splits a PDF scanned two pages per sheet into left and right pages. The downloadable Windows version; a browser version is available if you prefer not to install anything.
- Two-page Split (Browser) — Splits a two-page scanned PDF into single pages right in the browser, nothing to install. Files are never uploaded to a server. Same features as the Windows version.
- Scan PDF Cleanup — Makes yellowed, faint scanned books crisp again: whitens the background and darkens the text.