# Topic Notes

Notes around things I come back to often: Linux, networking, Docker, APIs, servers, debugging, deployments, and small infra details.

- URL: https://ilham.dev/guides/topics/
- Tool notes: https://ilham.dev/guides/tools/
- [API Testing](https://ilham.dev/guides/api-testing/) — Using OpenAPI files, mock responses, webhooks, gRPC testers, and request tools without copying blindly.
- [Browser Debugging Utilities](https://ilham.dev/guides/browser-debugging/) — Device info, network info, key codes, microphones, cameras, JavaScript playgrounds, and browser-side testing.
- [Browser File Tools](https://ilham.dev/guides/browser-file-tools/) — Small browser-side file tasks such as zip creation and Base64 conversion, with privacy boundaries.
- [Browser Games and Practice Tools](https://ilham.dev/guides/browser-games-and-practice-tools/) — Small browser games and practice utilities that live under tools without becoming blog posts.
- [Calculators and Unit Conversion](https://ilham.dev/guides/calculators-and-unit-conversion/) — Percentages, discounts, loans, interest, unit prices, currency, temperature, fuel economy, number bases, and roman numerals.
- [Dates, Timestamps, and Time Zones](https://ilham.dev/guides/dates-times-and-time-zones/) — Dates, durations, timestamps, time zones, age calculations, stopwatches, and ETA estimates.
- [Debugging CORS Without Guessing](https://ilham.dev/guides/debugging-cors/) — A practical way to reason about CORS errors, preflight requests, credentials, and browser behavior.
- [Docker Basics](https://ilham.dev/guides/docker-basics/) — Dockerfiles, Compose conversion, logs, and the small container details that matter during development and ops.
- [Email Debugging](https://ilham.dev/guides/email-debugging/) — Email headers, normalized addresses, suspicious messages, and the limits of what email metadata can prove.
- [Filtering Docker Logs Effectively](https://ilham.dev/guides/docker-logs/) — How to filter Docker container logs without losing useful context, timestamps, and failure clues.
- [HTTP and API Debugging](https://ilham.dev/guides/http-api-debugging/) — Requests, headers, auth headers, status codes, curl, MIME types, and small checks before blaming the API.
- [IDs and Test Data](https://ilham.dev/guides/ids-and-test-data/) — UUIDs, ULIDs, generated MAC addresses, and safe fake identifiers for tests and examples.
- [Indonesian Data Formats](https://ilham.dev/guides/indonesian-data-formats/) — NIK, phone numbers, spelled numbers, local salary estimates, maps links, and Indonesian text checks.
- [Linux Command Line Tasks Without Surprises](https://ilham.dev/guides/linux-command-line/) — Practical notes for find, grep, sed, xargs, chmod, cron, and other commands that are easy to misuse.
- [Network Debugging Notes](https://ilham.dev/guides/network-debugging/) — DNS, WHOIS, IP addresses, ports, subnets, MAC addresses, Wi-Fi QR codes, and SSH tunnels.
- [Nginx Reverse Proxy Configuration](https://ilham.dev/guides/nginx-reverse-proxy/) — Common nginx reverse proxy configuration patterns, headers, upstreams, TLS, and debugging checks.
- [Practical Image Tools](https://ilham.dev/guides/practical-image-tools/) — Image compression, format conversion, metadata removal, redaction, QR codes, placeholders, stickers, and watermarks.
- [Reading Logs Before Searching Randomly](https://ilham.dev/guides/reading-logs/) — Parsing logs, preserving context, checking timestamps, and narrowing down failures before random searching.
- [Security and Cryptography Basics for Developers](https://ilham.dev/guides/security-cryptography-basics/) — Hashing, encoding, signatures, keys, passwords, tokens, and crypto terms developers often meet while debugging systems.
- [SQL Formatting and Test Data](https://ilham.dev/guides/sql-formatting-and-test-data/) — Formatting SQL, generating inserts, and preparing small data sets for review or testing.
- [Testing and Debugging WebSockets](https://ilham.dev/guides/websocket-debugging/) — How to test browser WebSocket connections, inspect frames, and think about proxy-related failures.
- [Testing Regex Before Shipping It](https://ilham.dev/guides/regex-testing/) — How to test matching and replacement patterns before using regex in real code or shell commands.
- [Text Formatting and Cleanup](https://ilham.dev/guides/text-formatting-and-cleanup/) — Case conversion, line formatting, text statistics, Unicode, binary views, emoji, NATO spelling, and message formatting.
- [Understanding and Debugging JWTs](https://ilham.dev/guides/jwt-debugging/) — How to read JWT headers and claims, check expiry, and understand what signature verification does and does not prove.
- [Web Metadata](https://ilham.dev/guides/web-metadata/) — Meta tags, Open Graph previews, UTM links, and the page data used by browsers, crawlers, and social apps.
- [Working With Configuration Files](https://ilham.dev/guides/configuration-files/) — Reading, sorting, and editing configuration files without moving comments or changing meaning.
- [Working With PDFs](https://ilham.dev/guides/working-with-pdfs/) — PDF metadata, page extraction, merging, signatures, and browser-side document handling.
- [Working With Structured Data](https://ilham.dev/guides/working-with-structured-data/) — JSON, YAML, TOML, XML, CSV, JSONPath, schemas, diffs, viewers, and format conversion caveats.
- [Working With URLs](https://ilham.dev/guides/working-with-urls/) — Parsing URLs, encoding query strings, reading slugs, and checking redirected or wrapped links.
- [Writing and Publishing Text for the Web](https://ilham.dev/guides/writing-for-the-web/) — Markdown previews, HTML entities, slugs, URL encoding, and simple publishing tasks.