Reference category

Encoding & data

Encoding is a representation, not protection. Base64 turns bytes into text, UUIDs give records an identifier that does not require a central counter, and QR codes carry bytes into a camera. Each format has its own rules about length, padding, versioning and error correction, and those rules are what the entries document.

Use these pages when an encoded value fails to round-trip, when two systems disagree about a UUID version, or when a QR code is too dense to scan reliably. The paired tools let you reproduce the transformation and compare the result with the definition on the same screen.

Reference sets in this category (2)

QR Code Reference

How QR codes actually work: error correction, versions, capacity, quiet zones, mask patterns, Micro QR and the Wi-Fi QR payload format — each entry paired with a generator.

13 entries →

UUID Reference

UUID versions explained with the bits that matter: v4 randomness, v7 time ordering, v1/v3/v5 construction, the nil UUID, GUID differences and collision math — each with a generator.

11 entries →

All 24 entries

QR Code Reference 13 entries

QR error correctionFour levels — L, M, Q and H — trade payload capacity for tolerance of dirt, damage and glare. QR code versionVersions 1 to 40 set the grid size, from 21×21 to 177×177 modules. QR code capacityMaximum payload by mode and error-correction level, and why UTF-8 text uses more space than digits. QR encoding modesNumeric, alphanumeric, byte, kanji and ECI decide how many bits each character costs. QR quiet zoneFour empty modules on every side, required for the scanner to find the symbol. QR mask patternOne of eight XOR patterns applied to data modules to avoid large blank or blocky areas. QR format informationFifteen bits that tell the scanner the error-correction level and mask, protected by BCH. QR structured appendSplitting one payload across up to sixteen linked symbols. Micro QR codeA compact QR variant with one finder pattern, for very short payloads. Wi-Fi QR code formatThe WIFI: payload string that joins a network without typing the password. QR module sizeHow large each square must be printed for a camera to resolve it. QR code print sizeChoosing a physical size from module count, scan distance and surface. QR codes for binary and file dataWhen a QR code carries bytes rather than text, and why files rarely belong in one.

UUID Reference 11 entries

UUID format128 bits written as 32 hex digits in five hyphenated groups. UUID v4122 random bits — the default choice for identifiers that need no ordering. UUID v7A 48-bit Unix millisecond timestamp followed by random bits, for sortable identifiers. UUID v1Timestamp plus clock sequence plus node, historically a MAC address. UUID v3 and v5Deterministic identifiers derived from a namespace and a name via MD5 or SHA-1. Nil UUID00000000-0000-0000-0000-000000000000, the all-zero UUID. Max UUIDffffffff-ffff-ffff-ffff-ffffffffffff, the all-one UUID. UUID version and variant bitsThe fixed bits that tell a parser how the identifier was built. UUID collision riskWhy 122 random bits is safe at scale, and when name-based IDs collide deliberately. UUID vs ULIDTwo 128-bit identifiers with different text encodings and ordering guarantees. GUID vs UUIDMicrosoft's GUID is a UUID with platform-specific formatting and byte order.

Reference sets in this category (2)

QR Code Reference

UUID Reference

All 24 entries

QR Code Reference 13 entries

UUID Reference 11 entries

Tools that work with these entries

QR Code Generator

Wi-Fi QR Code Generator

Word Counter

Base64 Encoder

UUID Generator

Password Generator

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