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Journal

The IO Tools Journal

Guides, deep dives and field notes on the tools, formats and protocols developers use every day.

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APIsFeatured

Retry with exponential backoff and jitter: why your retries keep causing the outage

Exponential backoff without jitter just moves the stampede later. Full vs equal vs decorrelated jitter, how Retry-After should override your math, what to never retry, and a fetch wrapper you can paste.

Oct 24, 20267 min
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Web

HTTP cookie attributes: SameSite, Secure, HttpOnly, and the __Host- prefix that makes them stick

Oct 17, 2026 · 6 min
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Web

ETag and 304: how conditional requests revalidate a cache without re-downloading

Oct 10, 2026 · 4 min
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URLs

URL encoding: encodeURI vs encodeURIComponent, and the + vs %20 trap

Oct 3, 2026 · 5 min
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TLS

The TLS handshake, explained: what actually happens before HTTPS connects

Sep 26, 2026 · 8 min
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JWT

JWT signing algorithms: HS256 vs RS256 vs ES256, and why alg confusion still works

Sep 19, 2026 · 7 min
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Cryptography

RSA vs ECC: how public-key cryptography actually works

Sep 12, 2026 · 9 min
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Cryptography

The Playfair cipher: why pairing letters actually worked

Sep 5, 2026 · 7 min
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Cryptography

The Vigenère cipher: the code that called itself unbreakable

Sep 2, 2026 · 7 min
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Databases

UUID versions explained: v4, v7, and ULID

Sep 1, 2026 · 4 min
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Configuration

YAML vs JSON vs TOML: which config format should you actually use?

Sep 1, 2026 · 3 min
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Databases

Snowflake IDs: how Twitter and Discord pack a sortable ID into 64 bits

Aug 31, 2026 · 8 min
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Naming

Fáfnir, Smaug and Ao Guang Are Not the Same Kind of Name

Aug 24, 2026 · 5 min