jmespath-extensions

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Extended functions for JMESPath queries in Rust

3 stars RustOthers Updated Jul 3, 2026

jmespathjson

Documentation

jmespath-extensions

NOTE

This work has moved to https://github.com/joshrotenberg/jpx which includes a full JMESPath Specification

implementation with some performance improvements over the official crate, the full extensions (plus more) implemented here, a higher level "engine"

library that includes meta for both evaluation and function discovery, and the `jpx` CLI tool and the `jpx-mcp` MCP server.

No further development will be done on this repository.

Extended JMESPath with 400+ functions. Rust library and Python bindings.

Installation

Rust

toml

[dependencies]
jmespath_extensions = "0.9"

Python

bash

pip install jmespath-extensions

Usage

Rust

rust

use jmespath_extensions::search;
use serde_json::json;

let data = json!({"items": [1, 2, 3, 4, 5]});
let result = search("sum(items)", &data)?;
assert_eq!(result, json!(15));

// String functions
let data = json!({"name": "alice"});
let result = search("upper(name)", &data)?;
assert_eq!(result, json!("ALICE"));

// Date functions
let result = search("format_date(now(), '%Y-%m-%d')", &json!({}))?;

// Array functions
let data = json!({"values": [1, 2, 2, 3, 3, 3]});
let result = search("unique(values)", &data)?;
assert_eq!(result, json!([1, 2, 3]));

Python

python

import jmespath_extensions as jmx

# Basic usage
data = {"items": [1, 2, 3, 4, 5]}
result = jmx.search("sum(items)", data)
assert result == 15

# String functions
result = jmx.search("upper(name)", {"name": "alice"})
assert result == "ALICE"

# Array functions
result = jmx.search("unique(values)", {"values": [1, 2, 2, 3]})
assert result == [1, 2, 3]

Function Categories

Category	Examples
String	`upper`, `lower`, `split`, `replace`, `camel_case`, `pad_left`
Array	`first`, `last`, `unique`, `chunk`, `zip`, `flatten`, `group_by`
Math	`round`, `sqrt`, `median`, `stddev`, `percentile`
Date/Time	`now`, `parse_date`, `format_date`, `date_add`, `date_diff`
Hash	`md5`, `sha256`, `hmac_sha256`, `crc32`
Encoding	`base64_encode`, `base64_decode`, `hex_encode`, `url_encode`
Regex	`regex_match`, `regex_extract`, `regex_replace`
Geo	`haversine`, `geo_distance_km`, `geo_bearing`
Network	`cidr_contains`, `is_private_ip`, `ip_to_int`
JSON Patch	`json_patch`, `json_merge_patch`, `json_diff`
Fuzzy	`levenshtein`, `jaro_winkler`, `soundex`, `metaphone`
Expression	`map_expr`, `filter_expr`, `sort_by_expr`, `group_by_expr`

See docs.rs for the full function reference.

**jpx** - CLI, MCP server, and query engine built on this library
**JMESPath** - The query language specification
**jmespath.rs** - Rust JMESPath implementation

License

MIT or Apache-2.0

Frequently asked questions

What is jmespath-extensions?

jmespath-extensions is Extended functions for JMESPath queries in Rust

How do I install jmespath-extensions?

Open the GitHub repository and follow its README. Most MCP servers are added to your client's MCP config, then called by your agent.

Is jmespath-extensions open source?

Yes — it is hosted on GitHub at https://github.com/joshrotenberg/jmespath-extensions and has 3 stars.

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