https://hashitosystem.com/en/blog/ A tech blog on web development, algorithms, QR/barcodes, and Claude Code from Hashito System Inc. en Sun, 28 Jun 2026 00:00:00 +0900 https://hashitosystem.com/en/blog/binary-hex-explained/ https://hashitosystem.com/en/blog/binary-hex-explained/ Mon, 29 Jun 2026 00:00:00 +0900 From positional notation, why computers use binary, why hexadecimal is convenient, the conversion methods, and the worked example 255 = 11111111 = FF = 377, explained precisely. https://hashitosystem.com/en/blog/character-count-and-encoding/ https://hashitosystem.com/en/blog/character-count-and-encoding/ Mon, 29 Jun 2026 00:00:00 +0900 The number of characters in a text depends on how you count. This guide explains Unicode code points, UTF-8 variable-length bytes, and code units vs code points vs grapheme clusters with worked examples. https://hashitosystem.com/en/blog/color-codes-explained/ https://hashitosystem.com/en/blog/color-codes-explained/ Mon, 29 Jun 2026 00:00:00 +0900 The differences between HEX, RGB and HSL and how to convert between them, explained with a verified example (#3366cc = rgb(51,102,204) = hsl(220,60%,50%)). https://hashitosystem.com/en/blog/csv-vs-json/ https://hashitosystem.com/en/blog/csv-vs-json/ Mon, 29 Jun 2026 00:00:00 +0900 A precise guide to tabular CSV versus nestable, typed JSON, how to convert CSV⇄JSON, character encodings, BOM and delimiters, and when to use each. https://hashitosystem.com/en/blog/how-diff-works/ https://hashitosystem.com/en/blog/how-diff-works/ Mon, 29 Jun 2026 00:00:00 +0900 A precise look at the LCS that underlies diff, walked through with a small dynamic-programming example, how additions and deletions are derived, the Myers algorithm, and real-world uses. https://hashitosystem.com/en/blog/html-escaping-and-xss/ https://hashitosystem.com/en/blog/html-escaping-and-xss/ Mon, 29 Jun 2026 00:00:00 +0900 A precise guide to the characters HTML escaping targets, the danger of user input being interpreted as HTML, the reflected/stored/DOM-based types of XSS, defenses by output context, and CSP. https://hashitosystem.com/en/blog/naming-conventions-case-styles/ https://hashitosystem.com/en/blog/naming-conventions-case-styles/ Mon, 29 Jun 2026 00:00:00 +0900 A precise guide to the definition and an example of each case style, conventions per language and context, how to think about word boundaries, lint tools for consistency, and common mistakes. https://hashitosystem.com/en/blog/regex-basics/ https://hashitosystem.com/en/blog/regex-basics/ Mon, 29 Jun 2026 00:00:00 +0900 A precise guide to character classes, metacharacters, quantifiers, groups, anchors and flags, plus simple patterns for email, phone, URL and date, and pitfalls such as ReDoS. https://hashitosystem.com/en/blog/subnet-cidr-basics/ https://hashitosystem.com/en/blog/subnet-cidr-basics/ Mon, 29 Jun 2026 00:00:00 +0900 From the 32-bit structure of an IPv4 address to subnet masks and prefix length (/24 etc.), network/broadcast addresses, usable host counts, private addresses, and the math of subnetting, explained with tables and examples. https://hashitosystem.com/en/blog/text-processing-tips/ https://hashitosystem.com/en/blog/text-processing-tips/ Mon, 29 Jun 2026 00:00:00 +0900 Sorting lines, removing duplicates, stripping blank lines and surrounding whitespace, plus reversing and shuffling. A precise guide that also maps to command-line sort/uniq and the convenience of browser tools. https://hashitosystem.com/en/blog/what-is-base64/ https://hashitosystem.com/en/blog/what-is-base64/ Mon, 29 Jun 2026 00:00:00 +0900 How Base64 represents binary with 64 printable characters (3 bytes to 4 chars), use cases such as MIME and Data URLs, the UTF-8 caveat for Japanese, and URL-safe Base64, explained clearly. https://hashitosystem.com/en/blog/what-is-hashing/ https://hashitosystem.com/en/blog/what-is-hashing/ Mon, 29 Jun 2026 00:00:00 +0900 A precise guide to how hash functions work (one-way and deterministic), the properties of collision resistance and the avalanche effect, the difference from encryption, why SHA-256 is recommended, and the correct way to use hashing for password storage and tamper detection. https://hashitosystem.com/en/blog/what-is-json/ https://hashitosystem.com/en/blog/what-is-json/ Mon, 29 Jun 2026 00:00:00 +0900 A guide to JSON's six data types and syntax rules, common errors such as trailing commas, single quotes and full-width characters, and how to use formatting vs. minifying, all in line with RFC 8259. https://hashitosystem.com/en/blog/what-is-jwt/ https://hashitosystem.com/en/blog/what-is-jwt/ Mon, 29 Jun 2026 00:00:00 +0900 A precise guide to the header.payload.signature structure of JWTs, the registered claims, signatures with HMAC/RSA/ECDSA for tamper detection, the fact that the payload is not encrypted, where to use JWTs for stateless authentication, and security pitfalls. https://hashitosystem.com/en/blog/what-is-lorem-ipsum/ https://hashitosystem.com/en/blog/what-is-lorem-ipsum/ Mon, 29 Jun 2026 00:00:00 +0900 A precise guide to the meaningless placeholder text Lorem ipsum: its origin, why designers use meaningless characters, where it is used such as mockups and typesetting, and cautions like never leaving it in production. https://hashitosystem.com/en/blog/what-is-unix-time/ https://hashitosystem.com/en/blog/what-is-unix-time/ Mon, 29 Jun 2026 00:00:00 +0900 A precise guide to Unix time: the definition (seconds since 1970-01-01 UTC), seconds vs. milliseconds, time zones and UTC, ISO 8601, leap seconds, and the Year 2038 problem. https://hashitosystem.com/en/blog/what-is-url-encoding/ https://hashitosystem.com/en/blog/what-is-url-encoding/ Mon, 29 Jun 2026 00:00:00 +0900 A precise guide to the reserved and unreserved characters of RFC 3986, why encoding is needed, how % plus two hex digits encodes each UTF-8 byte, the difference between encodeURI and encodeURIComponent, and how forms handle it. https://hashitosystem.com/en/blog/what-is-uuid/ https://hashitosystem.com/en/blog/what-is-uuid/ Mon, 29 Jun 2026 00:00:00 +0900 A precise guide to UUID notation, the differences between versions, the structure of v4 (122 random bits), collision probability via the birthday problem, and where to use UUIDs in distributed systems. https://hashitosystem.com/en/blog/barcode-specifications/ https://hashitosystem.com/en/blog/barcode-specifications/ Fri, 26 Jun 2026 00:00:00 +0900 A guide to the characteristics and structure of EAN/JAN, UPC, CODE39, CODE128, ITF and Codabar, and how check digits work, explained alongside real generated samples. https://hashitosystem.com/en/blog/qr-code-specifications/ https://hashitosystem.com/en/blog/qr-code-specifications/ Fri, 26 Jun 2026 00:00:00 +0900 A guide to QR Code specifications, including versions, data capacity, encoding modes, error correction, structure, and masking, illustrated with real generated samples. https://hashitosystem.com/en/blog/claude-code-armin-ronacher/ https://hashitosystem.com/en/blog/claude-code-armin-ronacher/ Thu, 25 Jun 2026 00:00:00 +0900 claude-yolo with Docker, logging practices, agent-readable code design, and CLI over MCP. Armin Ronacher's approach explained with quotes from the original posts. https://hashitosystem.com/en/blog/claude-code-boris-cherny/ https://hashitosystem.com/en/blog/claude-code-boris-cherny/ Thu, 25 Jun 2026 00:00:00 +0900 Running Claudes in parallel, the habit of writing mistakes into CLAUDE.md, /commit-push-pr, the move to auto mode, 'verification 2-3x's the quality'. The creator's own practices, explained with sources. https://hashitosystem.com/en/blog/claude-code-documentation/ https://hashitosystem.com/en/blog/claude-code-documentation/ Thu, 25 Jun 2026 00:00:00 +0900 Based on our review of English-language sources, this article explains how to create, sync, and manage documentation with Claude Code. https://hashitosystem.com/en/blog/claude-code-how-top-engineers-use/ https://hashitosystem.com/en/blog/claude-code-how-top-engineers-use/ Thu, 25 Jun 2026 00:00:00 +0900 A look at how leading engineers around the world use Claude Code in practice, with references to the original articles. https://hashitosystem.com/en/blog/claude-code-mitchell-hashimoto/ https://hashitosystem.com/en/blog/claude-code-mitchell-hashimoto/ Thu, 25 Jun 2026 00:00:00 +0900 Delegating research, harness engineering, real examples from Ghostty, and the warning he calls 'agent psychosis.' We explain Mitchell Hashimoto's practice with quotes from his own blog. https://hashitosystem.com/en/blog/claude-code-project-workflow/ https://hashitosystem.com/en/blog/claude-code-project-workflow/ Thu, 25 Jun 2026 00:00:00 +0900 Based on research into English-language blogs, this article explains a project workflow for planning, implementing and verifying work with Claude Code. https://hashitosystem.com/en/blog/claude-code-simon-willison/ https://hashitosystem.com/en/blog/claude-code-simon-willison/ Thu, 25 Jun 2026 00:00:00 +0900 'Designing agentic loops', YOLO mode and sandboxes, the $5 disposable Fly.io organization. We explain Simon Willison's practices with quotes from the original articles. https://hashitosystem.com/en/blog/claude-code-team-collaboration/ https://hashitosystem.com/en/blog/claude-code-team-collaboration/ Thu, 25 Jun 2026 00:00:00 +0900 Based on a review of English-language blogs, this article explains how to build team collaboration, knowledge sharing, and communication around Claude Code. https://hashitosystem.com/en/blog/claude-code-test-scenarios/ https://hashitosystem.com/en/blog/claude-code-test-scenarios/ Thu, 25 Jun 2026 00:00:00 +0900 Based on research into English-language blogs, this article explains how to build test strategies, verification loops, TDD, and E2E verification with Claude Code. https://hashitosystem.com/en/blog/qr-code-error-correction/ https://hashitosystem.com/en/blog/qr-code-error-correction/ Thu, 25 Jun 2026 00:00:00 +0900 Through error correction levels (L/M/Q/H) and Reed-Solomon codes, we explain how a QR code still reads even when part of it is missing. https://hashitosystem.com/en/blog/sorting-algorithms-visualized/ https://hashitosystem.com/en/blog/sorting-algorithms-visualized/ Thu, 25 Jun 2026 00:00:00 +0900 An overview of how representative sorting algorithms work and their time complexity, with guidance on choosing the right one for the job. https://hashitosystem.com/en/blog/web-performance-core-web-vitals/ https://hashitosystem.com/en/blog/web-performance-core-web-vitals/ Thu, 25 Jun 2026 00:00:00 +0900 A practical guide to improving page speed and user experience around the three metrics LCP, INP, and CLS — from measurement to implementation.