Filesty Blog

Practical guides and tips about converting, compressing, and handling files - written by people who build file tools for a living.

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How to handle JWT expiration and token refresh

Why JWTs expire, what the exp claim really is, and how the access-token + refresh-token pattern keeps users logged in without long-lived credentials.

2026-07-04 · 8min read Read more ->

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JWT vs. session cookies: which should you use for authentication?

Stateless tokens or server-side sessions? A practical comparison of JWTs and session cookies - how each works, the real trade-offs, and when to pick which.

2026-07-04 · 8min read Read more ->

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Where to store a JWT: localStorage vs. cookies

localStorage is easy but XSS-exposed; cookies are safer but bring CSRF. A practical guide to storing JWTs on the client and the pattern most teams land on.

2026-07-04 · 7min read Read more ->

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5 real-world use cases for merging PDF files

If you've never needed to merge PDFs, count yourself lucky. For the rest of us, here are the five situations that come up again and again - and how to handle each.

2026-04-13 · 6min read Read more ->

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Base64 vs URL encoding: what's the difference?

Two encoding schemes that sound similar and are constantly confused. Here's what each one does, where they're used, and why you shouldn't mix them up.

2026-04-13 · 5min read Read more ->

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Common JSON errors and how to fix them

A field guide to the JSON errors you'll actually encounter in the wild - what they mean, where they come from, and how to fix them fast.

2026-04-13 · 7min read Read more ->

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Embedding images as Base64 in HTML/CSS: pros and cons

Data URIs let you inline images directly into HTML and CSS. Sometimes that's brilliant, sometimes it's terrible. Here's how to tell the difference.

2026-04-13 · 6min read Read more ->

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How to combine multiple PDFs into one file

A step-by-step guide to merging PDFs - what actually happens technically, how to control the page order, and how to avoid the common pitfalls.

2026-04-13 · 6min read Read more ->

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How to convert JPG to PNG without losing quality

A clear, honest guide to converting JPG to PNG - what quality is actually preserved, what isn't, and the best way to do it in 2026.

2026-04-13 · 6min read Read more ->

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How to format and validate JSON: a developer's guide

A practical guide to formatting JSON - what rules to follow, how to spot invalid JSON before it breaks production, and the shortcuts that save real time.

2026-04-13 · 6min read Read more ->

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How to reduce image file size for faster websites

Images are the heaviest thing on most web pages. Here's how to compress them properly - without destroying quality - and why it matters for SEO.

2026-04-13 · 7min read Read more ->

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JPG vs PNG: Which format should you use and when?

A practical breakdown of JPG vs PNG - how they compress, when each one wins, and a decision table you can actually use.

2026-04-13 · 7min read Read more ->

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JPG vs WebP vs AVIF: compression formats compared

A practical comparison of the three dominant raster image formats in 2026 - compression ratios, compatibility, and when to use which.

2026-04-13 · 7min read Read more ->

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JSON minification: when it matters and when it doesn't

Minifying JSON can save 30-50% file size - but only if it's going to matter downstream. Here's when to bother, when to skip it, and how to do it safely.

2026-04-13 · 5min read Read more ->

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What is Base64 encoding and when to use it?

A practical explanation of Base64 - what it actually does, why it exists, and the real situations where you'll need it.

2026-04-13 · 6min read Read more ->

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What quality setting should you use for web images?

The single most impactful image setting is one most people leave on the default. Here's what the quality slider actually controls and what to set it to.

2026-04-13 · 6min read Read more ->

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Why you shouldn't upload PDFs to random online tools

Online PDF tools are incredibly convenient - and one of the quietest sources of document leaks. Here's what actually happens to your files and how to stay safe.

2026-04-13 · 7min read Read more ->

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Why your logo should be PNG, not JPG

If your logo is saved as JPG, it's almost certainly hurting your brand. Here's what goes wrong and how to fix it in five minutes.

2026-04-13 · 6min read Read more ->