Image editing
Remove an Image Background Without Photoshop
Three ways to make an image background transparent without Photoshop: a free browser tool, AI services and GIMP - and how to avoid the usual failures.
Blog
Practical articles on building, testing and operating software.
Image formats
PNG vs WebP vs AVIF — Choosing and Converting
PNG, JPEG, WebP and AVIF compared on strengths, use cases and browser support, with how to serve them conditionally through the picture element.
Domains
Look Up Domain Info with Whois — Expiry, NS
What a Whois lookup actually shows - registrant, expiry, registrar, name servers - how GDPR changed the results, and how to use it day to day.
HTTP & networking
The Complete HTTP Status Code Guide
What the HTTP status codes developers actually meet mean - 200, 301, 403, 404, 413, 422, 429, 500, 502, 504 - why they happen and how to respond.
API & debugging
Convert cURL to fetch and Python requests
How to turn Copy as cURL from Chrome DevTools into fetch, axios, Python requests, PHP or Go, with a table of what each cURL option maps to.
Security
Cookie Security Flags — Secure, HttpOnly, SameSite
Cookie security attributes explained: Secure, HttpOnly, SameSite, the __Host- prefix and the 4096-byte limit, and what each stops - CSRF, XSS, hijacking.
Security & auth
JWT Security Best Practices — alg:none and Expiry
Six classic JWT vulnerabilities - alg none, key confusion, no expiry, secrets in the payload, no revocation, weak keys - and what to do about each.
Data & Excel
Open and Save CSV Correctly in Excel — UTF-8 BOM
Why CSV files come out garbled in Excel and how to fix it: producing UTF-8 with a BOM, the import route, and code samples in PHP and Python.
Nginx & servers
Set client_max_body_size Correctly in Nginx
The Nginx client_max_body_size default of 1m, where to set it, how it produces a 413, and how it interacts with upload_max_filesize in PHP.
Cloud & AWS
AWS S3 and CloudFront Upload Limits — Multipart
The AWS S3 limits (5 GB for a single PUT, 5 TB multipart), the CloudFront body limit and the 10 MB API Gateway cap - and how to work around them.
JavaScript & fetch
File Upload with fetch and axios — FormData
Implementing file upload with fetch and axios: using FormData, wiring a progress bar, chunking, error handling and the CORS settings that matter.
Laravel & PHP
Laravel File Upload Guide — Validation, Storage, S3
File uploads in Laravel: Request::file(), validating with mimes and max, saving through Storage::disk()->put(), and configuring the S3 driver.
PHP
File Upload in PHP — Validation, Storage, Security
File uploads in PHP explained: the shape of $_FILES, the UPLOAD_ERR codes, MIME validation with finfo, an extension allowlist and safe storage.
Cloud comparison
Ten Cloud Storage Providers — Limits and Pricing
Upload limits, free tiers and monthly pricing compared across ten providers - S3, GCS, Azure Blob, Cloudflare R2, Backblaze B2 - with how to choose.
Docker & PHP
PHP File Uploads in Docker — php.ini and Nginx
Configuring PHP uploads under Docker: upload_max_filesize and post_max_size in php.ini, a compose example for Nginx and PHP-FPM, and how to verify.
Next.js & React
Next.js File Upload Guide — App Router and S3
File uploads in the Next.js App Router: form actions, handling formData in route.ts, saving to Vercel Blob, uploading to S3 and showing progress.
Security
File Validation Checklist — Size, MIME, Magic Bytes
A production checklist for file uploads: size limits, MIME validation with finfo, an extension allowlist, magic-byte checks and a safe storage location.
Django & Python
Django File Upload Guide — FileField and S3
Covers FileField and ImageField, validation in forms.py, the MEDIA_ROOT and MEDIA_URL settings, and wiring S3 through django-storages.
Rails & Ruby
File Upload with Rails Active Storage — S3
File uploads in Rails with Active Storage: setup, has_one_attached and has_many_attached, validation, S3 configuration and image variants.
Go & backend
HTTP File Upload in Go — net/http, multipart and S3
File uploads in Go: receiving multipart with net/http, r.FormFile(), size limits, MIME validation and uploading to S3 with AWS SDK v2.
Vercel & Next.js
Vercel Upload Limits — Vercel Blob and Workarounds
Uploads on Vercel: the 4.5 MB bodySize limit on Functions, configuring vercel.json, using Vercel Blob, and uploading straight to S3 to sidestep it.
Netlify & JAMstack
File Upload with Netlify Functions — Limits
Uploads on Netlify: the 6 MB body limit on Functions, configuring netlify.toml, parsing multipart/form-data, and what to use instead of Large Media.
Render & cloud
File Upload on Render — Disks, Env Vars and S3
Uploads on Render: configuring a persistent Disk, setting upload_max_filesize for PHP, wiring S3 through environment variables and a Blueprint example.
Testing technique
How to Test File Upload Limits — Boundary Testing
Why upload limits are hard to test, and a practical boundary-value procedure using 9.9 MB, 10 MB and 10.1 MB threshold files against real services.
HTTP errors & servers
413 Request Entity Too Large — Causes and Fixes
What causes a 413 and how to clear it: client_max_body_size in Nginx, upload_max_filesize and post_max_size in PHP, and how to debug the mismatch.
HTTP errors & APIs
422 Unprocessable Entity — Validation Errors
When to return 422 rather than 400, how Laravel, Django and Rails use it, what it means for uploads, and the RFC 7807 problem-details format.
HTTP errors & ops
507 Insufficient Storage — Disk Space and S3
What triggers a 507 and how to recover: checking disk usage with df and du, keeping logs in check with logrotate, and cloud storage quotas.
Image formats
PNG vs WebP vs AVIF — Which Format Wins in 2026
PNG, WebP and AVIF compared on visual quality, file size, browser support and encoding speed, with a clear rule for which to pick when optimising.
Data processing
Fixing CSV Mojibake — Shift_JIS, UTF-8 and the BOM
Why CSV files break in Excel: the difference between Shift_JIS, UTF-8 and UTF-8 with BOM, plus encoding-conversion code in Python and PHP.
WordPress
Five Ways to Raise the WordPress Upload Limit
Five ways to raise the 2 MB default upload limit in WordPress: wp-config.php, .htaccess, php.ini, functions.php and the host control panel.
Reference
File Format Quick Reference — PNG, PDF, ZIP, CSV
A quick reference to the specifications, magic bytes, MIME types and maximum sizes of PNG, JPEG, PDF, ZIP, CSV and JSON - for writing validation.
File size
MB Is Not MiB — The File Size Unit Trap Explained
The difference between MB and MiB: how PHP and Nginx read the units, why Windows and macOS disagree, and what it means for boundary-value testing.
HTTP & networking
Calculating multipart/form-data Overhead Exactly
What makes up the 200 to 400 bytes of multipart/form-data overhead in an HTML form, how to calculate it, and how it eats into your size limits.
Encoding
Why Base64 Grows a File by 33% — The Formula
Why Base64 inflates data by about 33 percent, three bytes becoming four characters, and what that costs in API payloads, email and data URIs.
ZIP & compression
Why ZIP Compression Ratios Vary — Inside Deflate
Why text and CSV shrink by 60 to 85 percent while JPEG and MP4 barely compress, explained from how Deflate works - and when to use Store mode.