How to Remove Metadata from a PDF Before You Share It
What a PDF's hidden properties reveal about you, how to check them, how to remove metadata from a PDF in your browser, and what cleaning does not change.
· 7 min read
Developer guides
Practical guides for developers: data formats, encoding, regular expressions, debugging and more, with examples you can try in our free online tools.
Mermaid Diagram Syntax Guide: Flowcharts, Sequences, ER and More
A practical reference to Mermaid syntax for the six most useful diagram types, with GitHub rendering, a table of common parse errors and their fixes, and export options.
· 6 min read
GraphQL Schema to TypeScript Types: Nulls, Lists, Enums and Unions
How each part of a GraphQL SDL schema maps to TypeScript, from nullable list items to custom scalars and unions, with real converter output and advice on moving to a build-time code generator.
· 6 min read
.env Files Explained: Syntax, Secrets and Converting to JSON
The .env syntax rules that hold almost everywhere, where Node, PHP, Python and Docker Compose loaders disagree, how to keep secrets out of Git, and how to convert a .env file to JSON.
· 7 min read
CIDR Notation and Subnetting Explained with Worked Examples
How CIDR prefixes map to subnet masks and address ranges, how to split a /24 into aligned subnets by hand, and how private ranges and cloud reservations affect your plan.
· 5 min read
Subresource Integrity (SRI) Hashes: A Practical Guide
How Subresource Integrity stops a modified CDN file from running, how integrity values are built and verified, and how to handle upgrades, mismatches and files that change.
· 7 min read
How to Convert SQL Queries to MongoDB: find(), aggregate() and $lookup
A clause-by-clause guide to translating SQL into MongoDB find() calls and aggregation pipelines, with real converter output and the cases you still need to handle by hand.
· 6 min read
How to Format SQL: Readable Queries Across 20 Dialects
Practical rules for formatting SQL readably, with real formatter output and a comparison of identifier quoting, placeholders and dialect-only syntax across 20 SQL dialects.
· 13 min read
Linux File Permissions and chmod Explained: 644, 755 and Beyond
How read, write and execute work for files and directories, how to choose and apply octal or symbolic chmod modes, and how umask and the special bits fit in.
· 7 min read
Cron Expression Syntax Explained: Fields, Steps and Real Schedules
A field-by-field guide to standard cron syntax, with exact expressions for common schedules, the day-of-month and day-of-week OR rule, and how time zones work on Linux, Kubernetes and GitHub Actions.
· 6 min read
ULID vs UUID: Which Unique ID Should You Use?
A practical comparison of ULIDs with UUID v4, v7 and v1: how each is built, how they behave as database keys, and when to choose which.
· 7 min read
Snowflake IDs Explained: How to Decode the Timestamp
How Snowflake IDs pack a millisecond timestamp, machine ID and sequence into 64 bits, and how to decode them by hand or in code without losing precision.
· 6 min read