Reproducible checks, practical observations, and honest limitations—not generic file-format summaries.
Use the browser Network panel to check whether a file tool uploads your selected file, distinguish ordinary requests from uploads, and interpret the result accurately.
We saved one 1536×1024 PNG as WEBP and JPG at quality 40, 60, 80, and 95, then compared the measured file sizes with a PNG re-encode.
Choose between JPG, PNG, and the original HEIC for Windows, uploads, and sharing by comparing compatibility, file size, image characteristics, and metadata.
Understand why large image, PDF, audio, and video jobs can stall or close a mobile browser tab, and how memory copies, decoding, and main-thread work affect reliability.
We merged text-and-vector, image, and mixed PDFs, then compared page size, searchable text, embedded image data, and total file size before and after.
We cut the same three seconds from a 144MB MP4 with stream copy and re-encoding, then compared time, duration, size, and SSIM.
We converted the same music and speech WAV files to MP3 at 128, 192, 256, and 320 kbps, then explain the measured sizes, the 160 kbps ceiling for 24 kHz audio, and practical choices.
Understand why line breaks, tables, task lists, HTML, and images in one MD file can render differently because of syntax rules, extensions, styling, paths, and security policies.
See measured examples of how NBSP, zero-width spaces, and smart quotes change text length, UTF-8 size, search, splitting, and duplicate detection even when text looks the same.
See why line-level and word-level comparison report different change counts for the same revision, with measured examples and practical selection rules.
See why MP4 files can behave differently through hands-on tests with H.264, HEVC, video without audio, a renamed WebM file, and an incomplete file, followed by a practical troubleshooting order.
We changed QR margin, size, color contrast, data length, and error-correction level one factor at a time, then recorded what decoded and what failed.
A 33-second vertical video was compressed to 10 MB, 5 MB, and 2 MB at 1080p, 720p, and 480p to compare detail retention and processing time.