Guides
Anleitungen
Praktische Anleitungen und Einblicke zum sicheren Umgang mit Ihren Dateien im Browser. Jeder Artikel ist direkt mit dem entsprechenden Tool verknüpft.
When the Hometax e-Tax Invoice Secure Mail (NTS_eTaxInvoice.html) Won't Open
Why the HTML attachment from Korea's National Tax Service shows only a blank page or garbled text, and how to enter the password and read it in the browser with nothing to install. Limits stated plainly.
How to Check a Korean Digital Certificate's Expiry — Open signCert.der
How to see when your Korean joint certificate (formerly 'public certificate') expires before logging in to a bank or Hometax. Open signCert.der from the NPKI folder in the browser to see the validity period and issuer. No password needed.
How to Cut an MP3 — Trim Just the Part You Need, No Software (Ringtones, Highlights)
Trim MP3, M4A, or WAV to the section you need: pick the range on a waveform, add fades, make a ringtone. No install, no sign-up, no upload — it runs in the browser. What happens to audio quality is explained too.
How to Sign a PDF — Add a Handwritten Signature Without Printing or Scanning
How to sign a contract or consent form PDF you received by email and send it back: draw with a mouse or finger, or place a signature image, on the page and position you choose, then save a new PDF. No upload. Includes an honest note on legal validity.
Resize an Image to Exact Pixels — Set the Width and Height You Need
How to fit a photo to a required pixel size — ID photo specs, shop thumbnails, upload limits. Shrink without distortion using the ratio lock, and handle specs like 300×400 with crop plus resize. In the browser, no upload.
How to Add a Stamp to a PDF — Make a Seal Image and Place It Where You Need
Two steps to stamp a PDF quote, contract, or form: make a seal image (transparent PNG) from a name, then place it on the page and position you want with the PDF Sign tool and save. Using an existing stamp, and how this differs from a registered seal.
How to Watermark a Video — Channel Name or Logo, WYSIWYG
Stamp a copyright line or logo onto a video before sharing it. Position (9 spots), size and opacity adjust with a live preview, and the video is never uploaded.
How to Make a YouTube Thumbnail from Your Video — No Design App Needed
Pause on the best frame of your video, capture it, add a title, and save a 1280×720 thumbnail. Style presets give it structure even without design skills.