---
id: nested-lookup
version: "0.2.25"
license: Public Domain
license_treatment: permissive
maintenance: abandoned
---

# nested-lookup — Python functions for working with deeply nested documents (lists and dicts)

License: permissive · Maintenance: abandoned · Downloads: 389.4K/mo

## What it is and what it does

nested-lookup is a utility library for traversing and manipulating deeply nested Python data structures—typically dictionaries and lists parsed from JSON, YAML, or XML. It provides functions like nested_lookup (find all values for a key at any depth), nested_update (change values across all occurrences), nested_delete (remove keys), and nested_alter (apply a callback to matching values). By default these operations return a modified copy; you can pass in_place=True to mutate the original document.

The package supports optional features like case-insensitive substring matching (wild=True) and returning both keys and values. It also offers utility functions to enumerate all keys in a document, count key or value occurrences, and retrieve both occurrence counts and their associated contexts. No runtime dependencies are required.

Use it for:

- Extract all email addresses from a deeply nested configuration or API response document
- Update a specific field across all nested occurrences in a large JSON structure without manual recursion
- Audit a YAML configuration by finding all instances of a sensitive key like 'password' or 'api_key'
- Count how many times a particular value appears in a nested data structure for validation or debugging
- Transform nested numeric values (e.g., add 10 to all 'price' fields) using a callback function

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Provides functions to search, update, delete, and analyze keys and values across deeply nested dictionaries and lists, typically from parsed JSON, YAML, or XML documents.

No. The package is abandoned (last release 2022-07-06, 1500+ days ago) with no maintenance signals. While it has no known vulnerabilities and carries permissive licensing, the high install friction combined with lack of active support makes it risky for production use. For nested data manipulation, consider actively maintained alternatives or implement the logic directly in your codebase.

## Install

pip install nested-lookup
uv add nested-lookup
poetry add nested-lookup

## Installing nested-lookup

Before you install: High install friction reported. Package is abandoned as of 1500 days since last release, with no recent maintenance signals. Installs without runtime dependencies but carries the risk of unaddressed issues.

License in practice: Public Domain license permits unrestricted use, modification, and distribution with no attribution or liability requirements.

Quickstart:

pip install nested-lookup

from nested_lookup import nested_lookup
document = {'a': {'b': 42}, 'c': [{'b': 69}]}
result = nested_lookup('b', document)
print(result)  # [42, 69]

Verify before relying:

- Current compatibility with Python versions beyond 3.10 and modern dependency ecosystems
- Whether the package functions correctly with very large or deeply nested structures
- Active maintenance status and responsiveness to bug reports given the abandoned classification

## Package facts

- License: Public Domain (permissive)
- Python support: unspecified
- Install friction: high
- Maintenance: abandoned
- Downloads: 389.4K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

nested dictionary lookup, deep json traversal, find keys in nested structures, update nested document values, yaml dict manipulation, recursive key search, nested data extraction, data-structure-manipulation, unmaintained

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