---
id: jsonslicer
version: "0.1.8"
license: MIT
license_treatment: permissive
maintenance: abandoned
---

# jsonslicer — Stream JSON parser with iterator interface

License: permissive · Maintenance: abandoned · Downloads: 315.4K/mo

## What it is and what it does

JsonSlicer is a streaming JSON parser that reads JSON incrementally from a file or stream without loading the entire document into memory. It uses the YAJL C library for performance and provides a Python iterator interface. You specify a path pattern (using tuples of keys, array indices, or None as wildcards) and the parser yields matching objects as complete Python objects.

The package is designed for processing very large JSON files or continuous streams where memory efficiency matters. It supports multiple path modes to return just the objects, map keys alongside objects, or full path information. It has no runtime dependencies beyond the compiled C extension, making it lightweight once installed.

Use it for:

- Extract specific fields from multi-gigabyte JSON files without loading them into RAM
- Process streaming JSON APIs or log files line-by-line or chunk-by-chunk
- Iterate over all items in a deeply nested array or map using wildcard paths
- Parse JSON with optional features like comments or trailing garbage via YAJL flags
- Recover map keys alongside values when iterating dictionaries in JSON

## Worth the install?

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

Parses JSON streams and large files without loading them entirely into memory, using a path-based iterator interface to extract specific nested objects.

Yes, if you need to parse large JSON files or streams and your system has YAJL development headers available. The memory efficiency and speed justify the compilation overhead for that use case. No if you work with small JSON documents, prefer pure-Python solutions, or cannot manage C extension builds—the project is abandoned and may have compatibility issues on newer systems.

## Install

pip install jsonslicer
uv add jsonslicer
poetry add jsonslicer

## Installing jsonslicer

Before you install: High install friction: the package is written in C and depends on the YAJL library, requiring compilation. The project is abandoned (last commit 2022-10-25, 1389 days ago), so build issues on newer systems may not be addressed.

License in practice: MIT license is permissive and poses no restrictions on use, modification, or distribution in proprietary or open-source projects.

Quickstart:

from jsonslicer import JsonSlicer

with open('data.json') as f:
    for item in JsonSlicer(f, ('key', None)):
        print(item)

Requires YAJL development library and a C compiler to build the extension module during installation.

Verify before relying:

- Whether YAJL development headers are available on target systems without manual installation
- Compatibility with Python versions beyond 3.11 (classifiers list 3.6–3.11 only)
- Current build status on modern compilers and operating systems given the project's abandonment

## Package facts

- License: MIT (permissive)
- Python support: unspecified
- Install friction: high
- Maintenance: abandoned
- Downloads: 315.4K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

stream json parser, large json file parsing, memory-efficient json, json iterator, pull-based json parsing, json path extraction, incremental json reader, streaming-parser, c-extension, memory-efficient

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