Guides
Practical instructions for choosing options and checking the result.
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How to merge PDFs in the right order
Combine documents, supporting evidence and appendices into an ordered copy, then check it before sharing.
Read guideHow to split a PDF into pages or ranges
Separate chapters or pages into multiple files and learn when a single extracted selection works better.
Read guideHow to extract PDF pages into one file
Save selected pages and control the order of the copy while keeping the original document intact.
Read guideHow to duplicate PDF pages without changing their order
Add copies beside their originals and distinguish extra copies from total appearances.
Read guideHow to insert blank pages into a PDF
Create dividers or note space before or after selected sheets while matching their dimensions.
Read guideHow to number a PDF while leaving its cover unnumbered
Distinguish physical sheets from visible numbers and configure the sequence on the final document.
Read guideHow to add a watermark to a PDF
Identify drafts or copies with a readable notice and understand its limits as a protection measure.
Read guideHow to add a logo or image to a PDF
Prepare a sharp image, preserve readability and apply your logo to the final document version.
Read guideHow to convert JPG, PNG or WebP images to PDF
Order photos, receipts or screenshots and choose original dimensions or A4 while preserving proportions.
Read guideHow to interleave pages from two PDFs
Rebuild double-sided scans by alternating files and correct back-side pages saved in reverse order.
Read guideHow to split odd and even PDF pages
Create alternating groups, count from the first sheet and run a test before manual double-sided printing.
Read guideHow to crop PDF margins without confusing cropping with deletion
Hide scan borders with careful measurements and understand why contents may remain inside the file.
Read guideHow to add PDF margins for notes or printing
Enlarge sheets without scaling their contents and check dimensions and interactive elements in the copy.
Read guideHow to delete pages from a PDF
Remove unwanted sheets by number or range and keep the others in their original order.
Read guideHow to rotate a PDF and save its orientation
Correct sideways or upside-down sheets and save the change in a downloadable copy.
Read guideHow to reorder PDF pages with an exact sequence
Move, repeat or omit sheets by entering the complete order of the output copy.
Read guideHow to download and save a PDF on your phone
Find the downloaded copy, save previews and open ZIP archives produced by the tools.
Read guideHow to merge PDFs on your phone
Select phone documents, order them with touch controls and save a copy without installing another application.
Read guideHow to extract a single page from a PDF
Save a receipt or specific sheet as a standalone PDF and check its physical position.
Read guideHow to convert a PDF to text or images
Choose digital text extraction or JPG and PNG page images, then check the downloaded copy.
Read guideHow to inspect and edit PDF metadata
Check titles, authors and dimensions and understand the scope of metadata editing.
Read guideHow to reduce a PDF’s size without losing readability
Choose the compression level, understand what shrinks and what does not, and check the result before sending it.
Read guideHow to check that an online tool does not upload your files
Use your browser’s Network tab and offline mode to see whether a PDF, image or video tool uploads your file, and learn what that test can and cannot prove.
Read guideHow to prepare a confidential PDF before sharing it
Inspect the properties, edit what you can, delete the pages you cannot share, add a watermark and test the final copy.
Read guideHow to make a PDF from iPhone or Android photos without installing an app
Order your phone photos, turn them into a PDF for free with no sign-up, shrink it if needed and save the file to Files or Downloads.
Read guideHow to tell a PDF tool is really free, with no sign-up and no watermark
Learn the usual traps of “free” tools and run a two-minute test to check limits, sign-up, watermarks and whether your file is uploaded.
Read guideReduce the size of a PDF, photo or video without losing quality: what is possible and what is not
Understand when a file can get smaller without losing anything and when a small loss is unavoidable, and how to check the result before sending it.
Read guideText
5 guidesHow to count Unicode characters and words
Understand spaces, line breaks and emoji so you can interpret text counts accurately.
Read guideHow to clean and compare text lists
Define duplicate items and organize shared entries, differences and selected lines.
Read guideHow to extract links, emails and numbers from text
Choose the right extraction, turn HTML into text and review numbers and addresses without losing their context.
Read guideHow to clean text copied from a PDF and rename identifiers
Rebuild paragraphs broken by line breaks and convert names between camelCase, snake_case and other styles without mistakes.
Read guideHow to split text into chunks without separating emoji and accents
Choose visual characters or lines, interpret JSON output and reconstruct text without confusing characters, bytes and tokens.
Read guideImages
5 guidesPNG, JPG or WebP: what changes when converting an image
Choose by content and transparency, then compare the output without assuming it will always be smaller.
Read guideHow to resize an image without distortion
Calculate proportional dimensions and distinguish changing size from cropping the frame.
Read guideHow to reduce image file size without stretching it
Distinguish pixels from bytes and prepare a suitable image copy for a form or website.
Read guideHow to add image backgrounds, text and effects
Check transparency, dimensions and readability when preparing a modified image copy.
Read guideHow to remove location and metadata from a photo before publishing it
Learn what hidden data a photo carries, how to remove it in your browser and what information remains visible.
Read guideCalculators
7 guidesHow to calculate percentages and percentage change
Distinguish a percentage of a quantity, a proportion between quantities and change from an initial value.
Read guideDirect and inverse proportions: choosing with worked examples
Distinguish quantities that grow together from those that move in opposite directions and verify the formula with known values.
Read guideHow to calculate days, dates and ISO weeks
Distinguish intervals, working days and time zones before interpreting a date result.
Read guideHow to sum durations and estimate transfer times
Interpret minutes, hours, bits and bytes and check units before calculating.
Read guideHow to choose mean, median or weighted average
Interpret numeric lists and weights and understand what each average describes.
Read guideHow to calculate a loan payment and compare terms
Understand payment, interest and amortization, compare terms and learn what an indicative calculation leaves out.
Read guideHow to add and simplify fractions with prime factors and GCD
Choose a common denominator, reduce fractions and verify exact calculations with examples you can reproduce.
Read guideDeveloper
7 guidesHow to validate, format and minify JSON
Recognize syntax errors and understand what the browser’s JSON parser preserves.
Read guideHow to encode and decode Base64 with UTF-8 text
Convert accents and emoji correctly and distinguish encoding from encryption.
Read guideHow to convert CSV to JSON without losing leading zeros
Choose a delimiter, preserve codes as text and check quotes and rows before exporting a table.
Read guideHow to build and review URL parameters
Add queries without double encoding and check spaces, plus signs and repeated parameter names.
Read guideHow to compare JSON and query values by path
Distinguish formatting from data changes, read JSON Pointer paths and prepare review tables.
Read guideHow to verify a file with SHA-256
Compare file and text fingerprints and distinguish integrity, origin and security.
Read guideHow to read a JWT and understand what it contains
Discover the three parts of a JWT, what each date means and why decoding a token is not the same as validating it.
Read guideGenerators
5 guidesHow to generate and save random passwords
Choose length and character groups without treating a generated password as an absolute security guarantee.
Read guideHow to create and check a readable QR code
Encode text or direct links and verify contrast, margin and destination before sharing the code.
Read guideHow to create test data and organize random lists
Choose reproducible samples, sequences or random selections for the behavior you need to check.
Read guideHow to assign participants to random teams of balanced size
Prepare an unambiguous list, generate teams and check that nobody is missing or assigned twice.
Read guideHow to check color contrast on a website
Check text and background colors, interpret AA and AAA, and review sizes, states and gradients with reproducible examples.
Read guideVideo
9 guidesHow to trim and split a video with fast or precise cuts
Choose a cutting mode, plan your segments and check individual clips or a ZIP using a sample video.
Read guideHow to reduce video size and choose resolution, FPS and format
Understand compression, resolution, frame rate and containers so you can prepare a smaller copy that plays correctly.
Read guideHow to crop, rotate and watermark a video
Prepare a square or portrait frame and place visible text without covering important content.
Read guideHow to adjust, remove or extract a video’s audio
Choose between changing amplitude, removing the track and saving sound separately, with reproducible checks.
Read guideHow to capture a frame or create a video contact sheet
Save a chosen instant or summarize a recording in a timestamped PNG grid with verifiable examples.
Read guideHow to change a video’s speed, add fades, adjust color, hide an area and make a GIF
Change speed, fades, color, hidden areas and GIFs while checking every result against a sample video.
Read guideHow to reduce a video’s size for WhatsApp or email and convert MOV to MP4
Check what makes a video heavy, compress it, lower its resolution and convert an iPhone MOV to MP4 before you send it.
Read guideHow to hide faces, license plates and personal details in a video
Plan what must disappear, cover a fixed area with blur, pixelation or black, remove the sound and review the frames before you publish.
Read guideHow to make a small GIF from part of a video
Pick a short moment, set the start, length, width and frames per second, and keep the GIF light without uploading the video.
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