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Technical Articles

Read practical technical articles first, then use the related browser tools when you need to inspect or process something.
20 technical articles800+ words each
Technical articles800+ words
Read structureMerge pages

How PDF Files Work: Pages, Objects, Text Layers, and Merging

Compare bytesDecode text

UTF-8 vs Shift-JIS: Why Text Encoding Bugs Still Happen

Format JSONQuery paths

JSONPath for API Payloads: Querying Nested Data Without Writing a Script

Each article is written around a real technical topic instead of a reusable how-to template.

Use the articles to understand the format, boundary, and failure modes before opening a related tool.

Kept current

Articles are maintained around technical topics, privacy boundaries, and verifiable behavior.

Continue the task

Each article links back to relevant tools so you can finish the task after reading.

PDFPDF MergePage Order

How PDF Files Work: Pages, Objects, Text Layers, and Merging

cover.pdf + appendix.pdf + invoice.pdf
merged.pdf -> 24 pages
How PDF Files Work: Pages, Objects, Text Layers, and Merging

A practical explanation of how PDF files are structured, what really happens when PDFs are merged, and which details should be checked before sharing a final document.

7 min2026-05-17PDF MergerImage to PDF Converter
Open article
DeveloperUTF-8Shift-JIS

UTF-8 vs Shift-JIS: Why Text Encoding Bugs Still Happen

UTF-8: E3 81 82
Shift-JIS: 82 A0
UTF-8 vs Shift-JIS: Why Text Encoding Bugs Still Happen

A technical explanation of Unicode, UTF-8, Shift-JIS, byte sequences, mojibake, and how to debug encoding problems with small samples.

7 min2026-05-17Text Encoding ConverterBase64 Encoder / Decoder
Open article
DeveloperJSONPathPayload

JSONPath for API Payloads: Querying Nested Data Without Writing a Script

$.data.items[*].id
$..email
JSONPath for API Payloads: Querying Nested Data Without Writing a Script

A technical introduction to JSONPath as a debugging tool for nested JSON responses, including paths, filters, arrays, and implementation differences.

7 min2026-05-17JSONPath EvaluatorJSON Formatter
Open article
DeveloperCronNext Runs

Cron Expressions Explained: Fields, Time Zones, and Deployment Risks

0 9 * * 1-5
Mon-Fri 09:00
Cron Expressions Explained: Fields, Time Zones, and Deployment Risks

A technical article on how cron expressions are read, why schedules are misinterpreted, and how to verify future runs before deploying jobs.

7 min2026-05-17Crontab Expression Tool
Open article
UtilityUTCLaunch Window

Time Zones Explained: Offsets, IANA Names, DST, and Launch Planning

2026-05-16 16:00 UTC
09:00 PDT / 17:00 BST
Time Zones Explained: Offsets, IANA Names, DST, and Launch Planning

A technical article on why offsets are not time zones, how daylight saving changes schedules, and how to communicate launch windows clearly.

7 min2026-05-17Timezone ConverterTimestamp Converter
Open article
UtilityQR CodeDecode

QR Codes Explained: Payloads, Error Correction, Scan Distance, and Safety

https://uvlio.com/launch
scan back before sharing
QR Codes Explained: Payloads, Error Correction, Scan Distance, and Safety

A technical article on how QR codes store data, why payload length and error correction matter, and how to verify a code before publishing it.

7 min2026-05-17QR Code Generator / Decoder
Open article
UtilityEXIFGPS

EXIF Metadata Explained: GPS, Orientation, Camera Tags, and Privacy

GPS: removed before publish
captured on iPhone
EXIF Metadata Explained: GPS, Orientation, Camera Tags, and Privacy

A technical article on what EXIF metadata can reveal, why GPS and orientation fields matter, and how to review images before publishing.

7 min2026-05-17Image EXIF / GPS ViewerImage Watermark Tool
Open article
DeveloperHEXBytes

Hex and Bytes Explained: Reading File Headers, Encodings, and Binary Clues

50 4B 03 04
7B 22 69 64 22 3A 31 7D
Hex and Bytes Explained: Reading File Headers, Encodings, and Binary Clues

A technical guide to hexadecimal inspection, byte order, file signatures, BOM markers, and why byte-level debugging helps with format problems.

7 min2026-05-17Hex EditorBase Converter
Open article
DeveloperRSAPublic Key

RSA Keys Explained: Encryption, Signatures, Padding, and Private Key Safety

BEGIN PUBLIC KEY
encrypt short sample only
RSA Keys Explained: Encryption, Signatures, Padding, and Private Key Safety

A technical article on RSA public and private keys, why padding matters, how signing differs from encryption, and why demos are not key management.

7 min2026-05-17RSA Key Tool
Open article
DeveloperJSONCSV

JSON and CSV Are Not Equivalent: What Gets Lost During Conversion

{"name":"Ava","role":"admin"}
name,email,role
JSON and CSV Are Not Equivalent: What Gets Lost During Conversion

A practical technical article on converting between JSON and CSV, including nesting, headers, quoting, nulls, types, and spreadsheet assumptions.

7 min2026-05-17JSON ⇄ CSV ConverterJSON Formatter
Open article
DeveloperJWTClaims

JWTs Explained: Decoding Claims Without Confusing Them With Validation

header.payload.signature
"aud":"app-web"
JWTs Explained: Decoding Claims Without Confusing Them With Validation

A practical explanation of JWT structure, claims, Base64URL encoding, signatures, and why decoding a token is not the same as trusting it.

7 min2026-05-17JWT Decoder
Open article
Developerdocker runcompose.yaml

From docker run to Compose: What Each Flag Really Means

docker run -p 3000:3000 app
services: web:
From docker run to Compose: What Each Flag Really Means

A technical guide to translating docker run commands into Compose services while preserving ports, volumes, environment variables, restart rules, and secrets.

7 min2026-05-17Docker Run to Compose
Open article
DeveloperValidateFormat

JSON Validation vs Formatting: Syntax, Shape, and Schema Are Different

Unexpected token }
line 12, col 4
JSON Validation vs Formatting: Syntax, Shape, and Schema Are Different

A technical article explaining what JSON formatters can and cannot prove, how syntax differs from schema, and how to review payloads safely.

7 min2026-05-17JSON Formatter
Open article
DeveloperBase64Unicode

Base64 Explained: Encoding, Padding, Data URLs, and Common Mistakes

SGVsbG8gd29ybGQ=
decode -> Hello world
Base64 Explained: Encoding, Padding, Data URLs, and Common Mistakes

A technical article on how Base64 turns bytes into text, why padding exists, how URL-safe variants differ, and why Base64 is not encryption.

7 min2026-05-17Base64 Encoder / DecoderURL Encoder / Decoder
Open article
UtilityTimestampISO 8601

Unix Timestamps Explained: Seconds, Milliseconds, UTC, and Log Debugging

1715846400
2026-05-16T00:00:00Z
Unix Timestamps Explained: Seconds, Milliseconds, UTC, and Log Debugging

A practical guide to Unix timestamps, unit confusion, UTC display, JavaScript milliseconds, and how to read time fields in logs and APIs.

7 min2026-05-17Timestamp Converter
Open article
DeveloperUUID Generator

UUIDs Explained: Versions, Randomness, Sorting, and Safe Use

Pick version
Generate ID
UUIDs Explained: Versions, Randomness, Sorting, and Safe Use

A technical guide to UUID versions, why v4, v5, and v7 behave differently, and where UUIDs are useful or misleading in application design.

7 min2026-05-17UUID Generator
Open article
DeveloperSHA Hash Generator

SHA-256 Explained: Hashes, Integrity Checks, Salts, and Misuse

Hash input
Compare digest
SHA-256 Explained: Hashes, Integrity Checks, Salts, and Misuse

A practical guide to SHA-256 hashing, file integrity checks, password caveats, collision resistance, and why hashes are not encryption.

7 min2026-05-17SHA Hash Generator
Open article
DeveloperURL Encoder / DecoderBase64 Encoder / Decoder

URL Encoding Explained: Percent Encoding, Query Strings, and Safe Links

Identify part
Encode value
URL Encoding Explained: Percent Encoding, Query Strings, and Safe Links

A technical article on percent encoding, query parameters, path segments, form encoding, and why URLs break when reserved characters are copied raw.

7 min2026-05-17URL Encoder / DecoderBase64 Encoder / Decoder
Open article
DeveloperProtobuf Encoder / DecoderHex Editor

Protocol Buffers Explained: Schemas, Field Numbers, and Binary Debugging

Load schema
Decode bytes
Protocol Buffers Explained: Schemas, Field Numbers, and Binary Debugging

A technical introduction to protobuf payloads, why schemas are required, how field numbers work, and what to inspect when binary messages fail.

7 min2026-05-17Protobuf Encoder / DecoderHex Editor
Open article
UtilityImage Resize & CropImage Rotate & Flip

Image Formats Explained: JPEG, PNG, WebP, AVIF, HEIC, and Resizing Order

Resize first
Choose format
Image Formats Explained: JPEG, PNG, WebP, AVIF, HEIC, and Resizing Order

A practical technical article on choosing image formats, resizing before compression, preserving transparency, and preparing batches for upload.

7 min2026-05-17Image Resize & CropImage Rotate & FlipImage Format ConverterBatch Image ConverterImage Compressor & Converter
Open article