| Crypto | Cryptographic hashing and HMAC, digital signatures, authenticated encryption, random bytes, constant-time comparison, and Base64 and UUID helpers |
| CSS | A growing implementation of CSS-related utilities |
| Diff | A line-oriented textual difference implementation |
| DNS | DNS and hostname validation utilities |
| Email | E-mail address validation per RFC 5321 and RFC 6531, plus canonical account identity IRIs per RFC 6068 and RFC 7565 |
| GZIP | GZIP compression and decompression as per IETF RFC 1952 |
| HTML | A growing implementation of HTML generation utilities per the HTML Living Standard |
| HTTP | An implementation of HTTP-protocol parsing, formatting, and validation primitives per RFC 9110 |
| IDNA | Internationalized Domain Names in Applications (IDNA2008) utilities |
| IP | IPv4 (RFC 3986) and IPv6 (RFC 3986, RFC 4291) address validation |
| JOSE | Standards-driven primitives for validating JSON Web Tokens |
| JSON | A full-blown ECMA-404 implementation with read, write, and iterators support |
| JSONL | A JSON Lines (https://jsonlines.org) implementation with iterator support. Every non-empty line in a JSONL stream is a complete, valid JSON value, and lines are separated by newline characters (U+000A). Multi-line JSON values are not supported, as per the JSONL specification. Blank and whitespace-only lines are skipped rather than treated as errors. JSON Lines is a convention rather than a formal specification, so tolerating stray blank lines is friendlier to real-world input |
| JSON-LD | A JSON-LD 1.1 processor, with support for the JSON-LD 1.0 processing mode |
| JSONPath | A strict RFC 9535 JSONPath implementation |
| JSON Pointer | A growing implementation of RFC 6901 JSON Pointer |
| JSON-RPC | An implementation of the JSON-RPC 2.0 specification |
| LangTag | BCP 47 language tag validation utilities |
| Markdown | A growing implementation of Markdown-related utilities based on GitHub Flavored Markdown (GFM) |
| MCP | Helpers for building Model Context Protocol (MCP) envelopes |
| OAuth | A standards-driven implementation of the OAuth 2.0 and 2.1 message family |
| OpenID Connect | A standards-driven implementation of the OpenID Connect 1.0 message family |
| Punycode | An implementation of RFC 3492 Punycode |
| Regex | An opinionated and permissive ECMA 262 + RFC 9485 (best effort) regex implementation for JSON Schema |
| SemVer | An implementation of the Semantic Versioning 2.0.0 specification |
| Time | A growing implementation of time-related utilities for standards such as RFC 7231 (GMT) and RFC 3339 (Internet Date/Time Format) |
| Unicode | Unicode encoding utilities |
| URI | A strict RFC 3986 URI implementation, with RFC 3987 IRI syntax checking |
| URI Template | A strict RFC 6570 URI Template implementation |
| YAML | A YAML parser that converts YAML to JSON |
| Error | A growing collection of error utilities |
| I/O | A growing collection of I/O utilities |
| Numeric | Fixed-width integer types, decimal numbers, and numeric parsing and encoding utilities |
| Options | A simple and minimalistic UNIX-style command-line parsing library |
| Parallel | Growing collection of utilities for parallel computing |
| Process | Process related utilities |
| Stacktrace | A collection of utilities for interacting with stack traces |
| Test | A minimal unit testing framework |
| Text | A collection of general-purpose text manipulation utilities |
1.16.1 