deepmerge
A toolset for deeply merging Python dictionaries.
Decision gist · record as of 2026-08-14
Yes. deepmerge is production-stable (Development Status 5), actively maintained, has no known vulnerabilities, and solves a common problem with minimal dependencies and friction. Install it if you regularly merge nested dicts or need flexible control over how conflicts are resolved.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Low install friction with a single pure-Python dependency (typing_extensions).
- Active maintenance: last release 53 days ago, repository not archived, recent commits present.
License · maintenance · safety
MIT Licence (permissive) — MIT License (permissive) places no restrictions on use, modification, or distribution in proprietary or open-source projects.
last release 2026-06-22 (53 days) · last repo commit 2026-06-22 · 211 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 9,811,870 downloads/mo, #1,498 on PyPI
Alternatives
Verify before relying
pip install deepmerge
from deepmerge import always_merger
base = {"foo": ["bar"]}
next_dict = {"foo": ["baz"]}
result = always_merger.merge(base, next_dict)
# result: {'foo': ['bar', 'baz']}What it is and what it does
deepmerge handles the problem of combining nested Python data structures—dictionaries, lists, and sets—where simple assignment or shallow merging would lose data or overwrite values. It provides both a ready-to-use merger (always_merger) that applies sensible defaults and a Merger class for defining custom merge strategies per type. You specify how lists should combine (append, extend, or replace), how dicts should merge, how sets should combine, and what to do when types conflict or don't match any rule.
The package is lightweight, depends only on typing_extensions, and supports Python 3.8 and later. It's useful in configuration management, data aggregation, and any workflow where you need to combine nested structures without losing information from either source.
Use it for
- Merge configuration dictionaries from multiple sources (defaults, environment, user config) without losing nested settings.
- Combine API responses or JSON documents with overlapping keys while preserving list elements from both sources.
- Aggregate nested data from multiple files or database records into a single structure.
- Build custom merge logic for domain-specific data types using the Merger class with type-specific strategies.
- Handle YAML or JSON config merging in deployment or build tools where deep nesting is common.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
deepmerge is production-stable (Development Status 5), actively maintained, has no known vulnerabilities, and solves a common problem with minimal dependencies and friction. Install it if you regularly merge nested dicts or need flexible control over how conflicts are resolved.
Install
deepmerge on PyPI
Before you install
Low install friction with a single pure-Python dependency (typing_extensions). Active maintenance: last release 53 days ago, repository not archived, recent commits present.
License in practice
MIT License (permissive) places no restrictions on use, modification, or distribution in proprietary or open-source projects.
Quickstart
pip install deepmerge
from deepmerge import always_merger
base = {"foo": ["bar"]}
next_dict = {"foo": ["baz"]}
result = always_merger.merge(base, next_dict)
# result: {'foo': ['bar', 'baz']}Package facts
| License | MIT Licence permissive |
| Python support | Supports the current Python release >=3.8 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 1 packagetyping_extensions |
| Maintenance | Actively maintained 53 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 9,811,870 / month, #1,498 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 5 - Production/StableIntended Audience :: DevelopersLicense :: OSI Approved :: MIT LicenseProgramming Language :: Python :: 3 :: OnlyProgramming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.8Programming Language :: Python :: 3.9Typing :: Typed |
Evidence: deepmerge-2.1.0-py3-none-any.whl
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See also dict-recursive-update · hydraters · jsonmerge · merge3 · mergedeep · flatdict · nested-lookup · pytest-html-merger · datadiff · dpath