Introduction

This documentation covers the JMESPath Extensions project, which provides 400+ additional functions for JMESPath queries.

Project Components

This project includes multiple components:

This documentation primarily focuses on jpx, the CLI tool. For using the Rust library directly in your code, see the rustdoc documentation.

What is JMESPath?

JMESPath is a query language for JSON. It allows you to declaratively specify how to extract and transform elements from a JSON document.

Why JMESPath Extensions?

While standard JMESPath is powerful, it’s intentionally minimal with only 26 built-in functions. This project extends JMESPath with 400+ additional functions for:

• String manipulation: upper, lower, split, replace, camel_case, snake_case, and more
• Array operations: unique, chunk, flatten, group_by, zip, and more
• Object manipulation: pick, omit, deep_merge, flatten_keys, and more
• Math & statistics: round, sqrt, median, stddev, percentile, and more
• Date/time: now, format_date, parse_date, date_add, date_diff
• Hashing & encoding: md5, sha256, base64_encode, hex_encode
• Fuzzy matching: levenshtein, jaro_winkler, soundex
• And much more: geo functions, validation, regex, UUIDs, network utilities…

Features

• Rust Library: Use the functions in your Rust applications (docs.rs)
• Powerful CLI: Query JSON from files, stdin, or inline with jpx
• MCP Server: Use jpx with AI assistants like Claude
• Python Bindings: Use the same 400+ functions in Python
• Function Discovery: Built-in help for all functions
• Strict Mode: Use only standard JMESPath for portable queries

Quick Example

# Basic query
echo '{"users": [{"name": "alice"}, {"name": "bob"}]}' | jpx 'users[*].name'
# ["alice", "bob"]

# Using extension functions
echo '{"name": "hello world"}' | jpx 'upper(name)'
# "HELLO WORLD"

echo '{"items": [1, 2, 2, 3, 3, 3]}' | jpx 'unique(items)'
# [1, 2, 3]

echo '{"values": [10, 20, 30, 40, 50]}' | jpx 'median(values)'
# 30

Getting Started

Ready to dive in? Start with Installation to get jpx set up on your system.