flatwire (Python)

Streaming JSON serialization that keeps memory flat and time linear — stream large collections element-by-element instead of materializing the whole payload.

pip install flatwire

import flatwire

# Whole-value convenience (byte-compatible with the standard library).
data = flatwire.encode({"hello": "world"})
value = flatwire.decode(data)

# Stream a large collection to a binary writer, one element at a time.
with open("out.json", "wb") as fp:
    flatwire.encode_array((row for row in huge_iterator), fp)

# Read it back lazily — peak memory is one element, not the whole array.
with open("out.json", "rb") as fp:
    for row in flatwire.decode_array(fp):
        handle(row)

Wire format is plain JSON, so nothing downstream changes.

Streaming XML (v0.3)

The same API streams a typed, fully round-trippable XML representation — for which the standard DOM parsers would otherwise build the whole tree in memory:

# Stream a large collection as XML.
with open("out.xml", "wb") as fp:
    flatwire.encode_array(rows, fp, format="xml")        # optional: root="items"

# Parse it back lazily, one element at a time (iterparse under the hood).
with open("out.xml", "rb") as fp:
    for row in flatwire.decode_array(fp, format="xml"):
        handle(row)

Measured (bench/xml_bench.py): parsing a 12 MB document with ElementTree.fromstring peaks at ~125 MB, while flatwire's streaming parse holds ~4 MB (~97% lower); streaming encode is flat at ~900 bytes.

See the monorepo README for the cross-language story, and the live benchmark dashboard for the measured numbers.

Apache-2.0.