URL Parser Regex Extracts common URL components. Groups | Group | Description | |---|---| | scheme | Protocol scheme (http, ftp, etc.) | | host | Host name or IP address | | port | Port number | | path | Path part | | query | Query string | | fragment | Fragment identifier | Supports http://example.com ftp://example.com //127.0.0.1:80/path example.com/path?key=value#section URI-like strings with schemes Designed for .NET Regex. Extracts components but does not perform full RFC URI validation.

A .NET regular expression for extracting a single root-level JSON block from text. Supports: Root objects { ... } Root arrays [ ... ] Nested objects and arrays Escaped quotes inside strings Single-line comments // ... Multi-line comments /* ... */ This regex performs structural matching only. It validates balanced braces/brackets and ignores delimiters inside strings and comments. Features Captures the JSON block in the json group. Allows comments and whitespace before and after the JSON block. Uses .NET balancing groups for nested structures. Designed as a first parsing stage before actual JSON deserialization. Limitations This is not a full JSON parser. It does not validate: JSON syntax rules Property names Value types Duplicate keys Commas and separators Use a real JSON parser after extracting the block. Compatibility Requires a regex engine with balancing group support: ✅ .NET System.Text.RegularExpressions ❌ JavaScript RegExp ❌ Python re ❌ RE2 Example Input: // config { "name": "example", "items": [ 1, 2 ] } Results: Groups["json"] -> { "name": "example", "items": [1, 2] }

JSON Parser This regular expression is designed to tokenize JSON-like content embedded in INI files. It is not a full JSON validator; instead, it provides a lightweight lexical scanner that identifies structural tokens (objects, arrays, strings, numbers, booleans, null) and ignores comments and whitespace. The token stream is then processed by a hand‑written recursive‑descent parser (with depth‑limit protection) to build a .NET object graph (Dictionary, object], or primitives). Regex Pattern (?//.|/\.?\/)| (?""(?:\\.)"")(?=(?:\s|//.|/\.?\/):)| (?(?true)|(?false)|(?null)|""(?(?:\\.))""|(?-?(?:0|[1-9)(?:\.0-9]+)?(?:[eE?[0-9]+)?))| (?:)| (?\[)| (?,)| (?\])| (?{)| (?})| (?+)| (?[\r\n]+)| (?.+) Named Capture Groups | Group Name | Matches | |------------------|-------------------------------------------------------------------------| | comment | Single‑line //… or multi‑line /…/ comments (skipped). | | key | A JSON property key (double‑quoted string) followed by a colon (lookahead). | | value | A JSON value – one of: true, false, null, a double‑quoted string, or a number (integer, float, or scientific). | | bool | Sub‑group inside value for true/false (for direct parsing). | | null | Sub‑group for null. | | string | Sub‑group for the content inside double‑quotes (without the quotes). | | number | Sub‑group for numeric literals. | | value_sep | A colon : separating key and value. | | array_open | Left bracket [. | | array_sep | Comma , between array elements. | | array_close | Right bracket ]. | | object_open | Left brace {. | | object_close | Right brace }. | | whitespace | Horizontal whitespace (spaces, tabs) – not newlines. | | newline | Line‑break characters (CR, LF, CRLF). | | undefined | Any other character (should not occur in valid JSON; used as fallback). | Important Notes No recursion – the regex only tokenises; the parser handles nesting and depth limits. Escaped characters inside strings (\n, \t, \", etc.) are not unescaped by the regex – the parser calls UnEscape() when _allowEscapeChars is true. Whitespace and newlines are ignored by the parser (skipped during token iteration). The undefined group uses .+ (not .*) to avoid matching empty positions – this prevents false positives when the scanner reaches the end of the string. Purpose This regex is a solid foundation for building a custom JSON lexer, parser, or tokeniser for .NET projects. Its clear separation of structural elements, comments, and whitespace makes it easy to implement lightweight, hand‑crafted parsers that do not rely on heavy external libraries. It is particularly well‑suited for small to medium‑sized files, configuration blocks, or embedded data fragments, where performance and memory footprint matter. You can adapt the token stream to your own data model, add validation, or transform the JSON on the fly – all while keeping full control over the parsing logic.

Matches Scheme programs as described by https://small.r7rs.org/attachment/r7rs.pdf

Parses for formulas using glyph, unicode or sub/sup tags for the subscripts. TS script here (with screenshot)

Parses advanced chemical formula out of a paragraph of text

Matches for any element on the periodic table of elements

This matches some pretty complicated SMILES structures, works well for my app.

Matches for a chemical structure in a form similar to CHBF5-.K+. Accounts for every scenario I could think of (hydrates, adducts, ionic bonds, positive/negative charge indicators, etc)

Parses valid CAS numbers

from the lowest common div element, copy the html, and insert as the test string, then export

This regular expression is designed to tokenize XML content by identifying major XML constructs through named capture groups. It detects processing instructions (PI), DTD blocks, CDATA sections, comments, self‑closing tags, opening tags, closing tags, and plain text. It is suitable for building lightweight XML lexers or preprocessing XML before deeper parsing.

This regular expression is designed to tokenize XML content by identifying major XML constructs through named capture groups. It detects processing instructions (PI), DTD blocks, CDATA sections, comments, self‑closing tags, opening tags, closing tags, and plain text. It is suitable for building lightweight XML lexers or preprocessing XML before deeper parsing.

Gute KÄSE

wer den löwen weckt muss auch mit ihm tanzen

Regular expression to match a valid line of text in Halacae, a constructed language by R74n.

Regular expression to match valid words in Halacae, a conlang by R74n.

Regular expression to match valid URLs on R74n websites.

Code

plf HIIILLFFEEE

PLF hiilfe

Isch des Tüff

Wer den Löwen weckt muss auch mit ihm tanzen!

A regex to inspect other regex and match all capture groups

internal structure of a batch name

matches anime filenames. such as Group] Name [Episode[Audiometa]others.ext supports NCOP, NCED, OP, ED, SP, SPnn, nn, nn.n, nn.n_vn mp4, mkv, srt, ass but you could add more. the episode must be written within a [] bracket. finally, this regex cannot cover all the cases and obviously have some issues, but it's fine under most cases. it is also a small regex practice for me.

This is a GitHub Advanced Security (GHAS) Secret Scanning Custom Pattern I created to detect likely hardcoded credentials while reducing common false positives in code. Goal: detect assignments for these key names: password secret apikey / api_key / api-key Pattern regex: (?i)\b(password|secret|api[-]?key)\b\s[:=]\s(?!\s\$\{)(?!\sprocess\.env\b)(?:['"])?[A-Za-z0-9!@#$%^&()+=-]{5,}(?:['"])? What it should catch (examples): password: "ahsjdfahsjfhdjsahj" secret = 'kjfskahfsdhfj' apikey: ABCDE12345!@# (unquoted) What it tries NOT to catch (common false positives): password: ${password_somename} (template/variable placeholder) secret: ${VAULT_SECRET} password: process.env.DB_PASSWORD (env var reference, not a hardcoded secret) This is intended as a practical baseline; it won’t be perfect for every language/config style. If you have suggestions to improve the detection accuracy (reduce false positives/false negatives) for GHAS custom patterns, please share.

Finds CSS selectors that only contain one line and, using the substitution, flattens everything to be on the same line.

Matches and verifies IP address. 192.168.0.1 Matches 999.999.9.9 Didn't match

52 character long regex to validate IP address.

selects numbers, with commas and decimals, like 1,234.56

Grabs the outer parentheses and contents taking into account inner parentheses enclosures

matches composer packages with -alpha, -beta and -rc versionings

Regex showing how to match the five parts in an OmegaT project name (named as per the internal convention at cApStAn), including labels for each captured group (each part in the name).

match: #aabbcc #abc (255,255,255) (255,255,255,255) 255,255,255 no match: #gggggg #ggg 256,256,256

Selects the ` and ` tags from a string. You can probably do this with something easier, but this works

Regex for Door_Double

ตรวจสอบพยัญชนะต้น (ต้องมี) ตรวจตัวสะกดสำหรับสระที่ต้องมี ตรวจสอบการวางสระและวรรณยุกต์ไทย หมายเหตุ การตรวจสอบตัวสะกดในภาษาไทยตรวจสอบได้ยากเพราะภาษาไทยเป็นภาษาที่เขียนติด ๆ กันไม่มีการแบ่งคำอย่างชัดเจนทำให้การอ่านภาษาไทยผู้อ่านต้องใช้ความหมายของคำในการตัดสินการอ่านแบ่งคำตามความเหมาะสมเช่นคำว่า "ตากลม" อาจอ่านเป็น "ตาก-ลม" ก็ได้ หรืออ่านเป็น "ตา-กลม"ก็ได้ ดังนั้นการเขียน Regex เพื่อทำการตรวจสอบอาจช่วยได้ระดับหนึ่ง อ่าจมีผิดบ้างถูกบ้าง แต่ก็ถือว่าเป็นเครื่องมือที่ใช้ช่วยเหลือในการตรวจสอบเพิ่มเติมได้ 80% ของความเป็นไปใด้ก็แล้วกันนะครับ หวังว่าการเขียนเพิ่มเติมส่วนนี้ จะมีประโยชน์บ้างไม่มากก็น้อย

This regular expression provides a balance between RFC compliance and security-best-practices. It is designed to prevent injection vectors in legacy systems by using a restricted "safe" character subset recommended by the OWASP Validation Regex Repository. Pattern: ^A-Za-z0-9(?:\.A-Za-z0-9_+&-]+)*@(?:[A-Za-z0-9{0,61}[A-Za-z0-9])?\.)+[A-Za-z]{2,63}$ Key Features: Forced Alphanumeric Start: Prevents leading hyphens to avoid command injection vulnerabilities. Security Subset: Restricts special characters to _+&*- to prevent exotic character injections (e.g., pipes or backticks). No Quoted Strings: Forbids quoted strings to eliminate dangerous payloads containing spaces or backslashes. DNS Compliance: Enforces label lengths (1–63 characters) and prevents labels from starting or ending with hyphens. Whole String Anchoring: Uses ^ and $ to ensure the entire input is validated.

Extracts the following fields from a Laravel Log print: Time Stamp (Date) Log Level (supports optional prefix (ie. local.DEBUG)) Log Message Exception | Context If an exception is detected, the file reference (file path + line number), and optional stacktrace are captured.

Correct Poland PESEL base regex validator. Covers birth dates up to 2099 year. PESEL numbers are in YYMMDDXXXXX format, however, the month is adjusted based on what year people were born. People born from 1900-1999 has no adjustment, 2000-2099 is the month +20, 2100-2199 is +40, 2200-2299 is +60. For example, if someone was born December 16, 2016, their PESEL would be 163216XXXXX.

PLF4

PLF3

PLF2

plf1

hey das ist richtig coool oder?

This is a Python RE for matching different parts and combinations of various docker/container image references, as compatible with docker pull etc. Parts / Capture Groups image: # whole image repo: # everything but the tag/digest registry: # host+port host: port: name: # path within registry reference: # tag or digest (with : or @; I haven't bothered to figure out how to strip that yet) tag: digest: If it matches, it should match image, repo, and name at the very least.

Simple prefix matcher for validating URI Schemes according to [RFC2396, Section 3.1]( http://www.faqs.org/rfcs/rfc2396.html#3.5:~:text=well%20as%20%22http%22%29.-,scheme%20%20%20%20%20%20%20%20%3D%20alpha%20*%28%20alpha%20%7C%20digit%20%7C%20%22%2B%22%20%7C%20%22%2D%22%20%7C%20%22.%22%20%29,-Relative%20URI%20references) Go Playground: https://go.dev/play/p/vtYEugsNAfo

URL, URI format validation

Used to check Email Format