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Developer Guides
In-depth guides for common developer tasks.
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Check Japanese Character Limits Before Submitting Essays and Entry Sheets
A practical workflow for checking Japanese character limits before submission so a draft does not fail because it is visibly short, quietly over, or counted under the wrong rule.
Data Tools Hub: JSON, CSV, SQL, Timestamps, and Developer Payload Workflows
A hub guide to choosing the right data tool for JSON, CSV, SQL, timestamps, cron expressions, and structured debugging workflows.
How to Debug REST API Responses
A practical guide to reading, validating, and decoding API responses - JSON formatting, Base64 decoding, URL decoding, and timestamp conversion.
Fansub Subtitle Workflow Hub: Danmaku, ASS, SRT, WebVTT
A practical workflow guide for fansub and anime subtitle pipelines: convert Bilibili danmaku to ASS, swap between ASS/SRT/WebVTT, and re-sync timing for different frame rates.
Japanese Writing & Content Creation Hub: Counters, Readability, and Romanization
A workflow hub for Japanese writers, teachers, and content creators — character counters, kanji density, JLPT level checking, romanization, manuscript paper, and reading-time estimation in one map.
Complete Guide to Japanese Zenkaku & Hankaku for Banking and Registration
Why do Japanese banks still require half-width Katakana? Learn the history of Zenkaku/Hankaku and how to correctly format your name for Japanese forms.
JSON Formatter vs JSON Validator: Which Tool Should You Use First?
A practical comparison of JSON formatters and validators, including when to beautify, when to validate, and how to combine both in one debugging workflow.
JWT Debugging Checklist: Claims, Expiry, Signatures, and Common Mistakes
A practical JWT troubleshooting guide covering claim inspection, expiry checks, token structure, and adjacent auth debugging steps.
Language Tools Hub: Japanese Writing and Language-Specific Utility Workflows
A hub guide to Japanese-focused tools and the broader strategy for language-specific developer utilities.
Media Tools Hub: Image, Color, and Subtitle Workflows for Frontend Teams
A hub guide to image compression, color conversion, subtitle handling, and media utility workflows in the browser.
How to Debug Redirect URLs, Query Params, and Encoded Targets
A web debugging guide for decoding redirect targets, checking nested query parameters, and spotting double-encoded URLs.
Security Tools Hub: JWT, UUID, Password, and Token Utility Workflows
A hub guide to JWT decoding, password generation, UUID workflows, and security-adjacent developer tooling.
Text Tools Hub: Regex, Markdown, Diff, and Content Cleanup Workflows
A hub guide to regex testing, markdown previewing, diff checking, and text analysis workflows for developer content and copy.
Web Tools Hub: Encodings, URLs, Headers, and Browser Debugging Workflows
A hub guide to URL, Base64, headers, request helpers, and browser-facing web debugging workflows.
How to Clean Up and Inspect Webhook Payloads Quickly
A workflow guide for untangling webhook payloads with JSON formatting, URL decoding, Base64 inspection, and timestamp conversion.
All guides
400 vs 401 vs 403 vs 422: A Practical API Error Triage Workflow
A concrete debugging workflow for separating malformed requests, authentication failures, permission issues, and validation errors before your team fixes the wrong thing.
Why Access-Control-Allow-Origin Star Fails with Credentials
A practical browser-first guide to diagnosing the most common credentialed CORS mistake: returning wildcard Allow-Origin while the frontend sends cookies or auth-bound credentials.
CSV to SQL Data Import: The Database Migration Boundary
Learn how to safely and correctly import CSV data into databases. Understand type mapping, SQL dialects, and common pitfalls in data migration workflows.
encodeURI vs encodeURIComponent for redirect_uri and Query Params
A practical guide to choosing the right encoding boundary for redirect_uri, nested URLs, and query parameter values before a small encoding mistake turns into a redirect bug.
The .env Configuration Boundary: Why Validation Before Deployment Matters
Understand why environment variable validation is critical—prevent configuration disasters, exposed secrets, and runtime failures. Learn the validation boundary between local development and production.
Estimate Japanese Reading Time for Scripts, Lessons, and Study Content
A workflow for estimating Japanese silent reading and read-aloud time so scripts, lessons, and study materials fit their real timing constraints.
How to Read User-Agent Strings Without Overthinking Every Token
A practical guide to extracting the few user-agent signals that actually change debugging decisions, including browser family, OS, device type, and likely bot markers.
Check IPv4 CIDR Boundaries Before You Touch Firewall Rules
A practical workflow for checking subnet boundaries, broadcast scope, and usable host ranges before a firewall or allowlist change widens the wrong network.
Nested Redirect URL Debugging Checklist: Duplicate Params, Empty Trackers, and Decode Boundaries
A practical workflow for debugging redirect URLs that hide duplicate query keys, empty tracking params, and half-decoded nested values.
no-store vs no-cache vs max-age for HTML, APIs, and Versioned Assets
A practical caching guide for choosing the right Cache-Control strategy for authenticated HTML, revalidating APIs, and long-lived static assets before copied directives start conflicting.
The Three Percentage Questions Everyone Confuses — and How to Solve Each
Most percentage errors come from applying the wrong formula to the wrong question. Learn to identify which of the three percentage calculations you actually need.
Prisma Relation Review Before Migrate and Generate
A practical review workflow for catching ambiguous relations, missing IDs, and misleading model boundaries before Prisma migrate or generate turns them into noisy downstream errors.
Why Your redirect_uri Breaks: Nested Params, + Signs, and Double Encoding
A practical guide for redirect_uri bugs caused by nested query strings, plus-sign handling, and accidental double encoding across browser and server layers.
URL Encoding Explained: When and Why to Percent-Encode
Why certain characters must be encoded in URLs, the difference between encodeURI and encodeURIComponent, and when double-encoding happens.
UUID v4 in Practice: Generation, Storage, and Common Pitfalls
How UUID v4 works, when to use it over other ID strategies, storage considerations, and common mistakes with database primary keys.
When to Use Genkouyoushi Counts Instead of Raw Character Count
A practical guide to when Japanese writing should be thought of in manuscript-paper sheets instead of raw characters, especially for assignments, essays, and draft planning.
Why Set-Cookie Fails Even When the Response Looks Correct
A debugging guide for separating browser cookie policy rejections from backend response success when auth cookies appear to vanish after login.
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