Golit

Reactive data apps that actually ship.

A high-performance reactive Directed Acyclic Graph (DAG) framework for Python. Golit maps your data dependencies once, then on every interaction recomputes only the nodes that changed — not your whole script.

Documentation · Changelog · Examples · Benchmarks · Architecture · Deployment

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Golit pairs the authoring speed of a notebook-style data app with the runtime discipline of a compiled reactive graph. Your dashboard is a set of plain Python functions; Golit infers the dependency graph between them, and a Rust kernel ensures a user interaction re-runs the minimal subgraph it touched and ships only the affected HTML fragments over the wire. The guiding thesis: update cost is proportional to the change, not the size of the program.

Features

• Rust reactive kernel (PyO3) — dirty tracking, topological scheduling, memoized propagation.
• Polars data held Python-side; only node ids/hashes cross the FFI boundary. Nodes may return LazyFrames — plans fuse across node boundaries and collect once at the view, with an opt-in path to the streaming engine for larger-than-memory data.
• SQL nodes — reactive nodes written as in-process DuckDB SQL over Polars frames (golit.sql).
• Litestar orchestration with HTMX server-rendered fragment transport — no client framework.
• Charts — Lets-Plot static SVG, plus interactive Plotly / Altair / Bokeh / AnyChart.
• Tables — styled tables from Polars, or return a Great Tables GT object for a polished, auto-rendered display table.
• Maps — native MapLibre GL: GeoDataFrame vector, rioxarray/xarray raster, and DuckDB spatial SQL (golit.gis).
• Components — reactive input widgets plus a shadcn-styled golit.ui library, server-rendered with Tailwind.
• Realtime — SSE push with pluggable pub/sub (in-memory or Redis), WebSocket chat, video (server-side MJPEG + browser-camera CV), and audio (mic recorder).
• Live sources — @app.poll streams external data that changes on its own (a Google Sheet, an API); only real changes re-render and hit the wire.
• Scales horizontally — N single-worker instances behind a sticky load balancer with Redis fan-out.

Installation

Golit ships prebuilt wheels for Python 3.11+ (the abi3 stable ABI):

pip install golit                 # core
pip install "golit[charts]"       # interactive Plotly / Altair / Bokeh
pip install "golit[sql]"          # DuckDB SQL nodes over Polars frames
pip install "golit[gis]"          # native MapLibre maps from GeoDataFrames
pip install "golit[gis-raster]"   # raster maps from rioxarray/xarray arrays
pip install "golit[tables]"       # Great Tables display tables (auto-rendered from a view)
pip install "golit[vision]"       # webcam / MJPEG video streams (Pillow)
pip install "golit[vision-cv]"    # + OpenCV for real CV models (face detection)
pip install "golit[redis]"        # Redis fan-out for multi-worker

Quickstart

make dev     # uv venv (3.11) + deps + build the Rust kernel (maturin)
make test    # cargo test + pytest
make run     # golit run examples/sales_explorer/app.py

Then open http://127.0.0.1:8000.

Programming model

Nodes are plain Python functions. Dependencies are inferred from parameters: a parameter named after another node is an edge; a parameter defaulting to a widget is an input.

import polars as pl
from golit import App, create_app, slider, upload
from golit.charts import aes, geom_bar, ggplot, ggsize

app = App(title="Sales Explorer")

SAMPLE = pl.DataFrame({"region": ["North", "South", "East", "West"], "revenue": [120, 90, 70, 40]})

@app.source
def data(file=upload("Upload CSV")) -> pl.DataFrame:
    return SAMPLE if file is None else pl.read_csv(file)   # renders before any upload

@app.reactive
def filtered(data: pl.DataFrame, threshold: int = slider(0, 100, default=20)) -> pl.DataFrame:
    return data.filter(pl.col("revenue") > threshold)   # re-runs only when data/threshold change

@app.view
def chart(filtered: pl.DataFrame):
    return ggplot(filtered, aes("region", "revenue")) + geom_bar(stat="identity") + ggsize(640, 360)

application = create_app(app)   # an ASGI app; `golit run app.py` serves it

Moving the slider dirties threshold → filtered → chart. The data node is never touched; only the chart fragment is re-rendered and swapped. A view that depends only on data (e.g. a dataset overview) is not re-rendered on a slider move — that selective recompute is the whole point. See examples/sales_explorer/app.py.

How a change flows

1. POST in — a committed input (hx-post) runs the dirty subgraph; the response carries only the affected view fragments as out-of-band HTMX swaps.
2. SSE out — nodes dirtied server-side (streaming sources, background jobs, shared nodes) are pushed over /events as named node:<id> events.
3. Memoization — a node re-executes only when its inputs hash differently; an unchanged output cascades into memo hits downstream (nothing on the wire).

Performance

The thesis is update cost is proportional to the change, not the program — and the benchmark harness measures it (dev laptop, loopback; reproducible, not yet the published cloud figure). The honest summary:

• A single filter → chart updates in ~2 ms over HTTP — the same as Dash. Idiomatic Dash is a hand-wired reactive DAG, so on one chain both do identical work and tie. Saying otherwise would be a strawman.
• The gap opens on the shape real dashboards have: shared upstream work. When one expensive step (a load, a join, a sort) feeds several views, moving a control that touches only one view makes Golit re-run only that view — the shared upstream is memoized and executes zero times — while Dash recomputes it every callback. Over real HTTP that's ~1.6× faster at 100K rows, ~5.5× at 1M, ~8.3× at 2M, and the lead widens with the app.
• chart_spec skips the figure object. Returning a raw spec dict instead of a go.Figure cuts the per-update round-trip to ~1.5 ms and ~635 B (vs ~6.9 KB) — ~1.4× faster than figure-returning Dash with a ~10× smaller payload, same chart.

See bench/README.md for the methodology and one-command repros.

SQL nodes

A reactive node can be written as SQL instead of Polars. golit.sql(query, **frames) runs DuckDB in-process over the named upstream frames and returns Polars, so the node memoizes and renders like any other — inputs feed straight into the query.

from golit import sql

@app.reactive
def by_region(data: pl.DataFrame, threshold: int = slider(0, 200, default=40)):
    return sql(
        "SELECT region, sum(revenue)::BIGINT AS revenue "
        f"FROM d WHERE revenue > {int(threshold)} GROUP BY region ORDER BY region",
        d=data,
    )

DuckDB exchanges data with Polars zero-copy. A raw duckdb.sql(...) relation returned from a node is auto-detected and materialized too. Optional dependency: pip install "golit[sql]"; it is imported only inside sql(), never at framework import time. See examples/duckdb_sql/app.py.

Charts

Lets-Plot renders to static SVG (no client runtime). For interactivity, return a Plotly, Altair, or Bokeh figure — Golit auto-detects it and renders a client-side chart that hydrates on the initial load and across POST/SSE swaps. AnyChart (no Python package) is available via anychart().

@app.view
def chart(by_region):
    import plotly.express as px
    return px.bar(by_region, x="region", y="revenue")   # Polars frame in directly

For a view that rebuilds its chart on every interaction, chart_spec(lib, dict) hands Golit the raw wire-format spec directly, skipping the figure-object build and to_json (see Performance). See examples/charts_gallery/app.py.

Maps

A map is a reactive view like any other — a control rebuilds it. Return a GeoPandas GeoDataFrame and Golit renders a native MapLibre GL map; golit.gis.geo_map adds choropleths, tooltips, and basemaps, and golit.gis.spatial_sql runs DuckDB ST_* queries that feed it. No client map framework — the server ships the GeoJSON and the style rules; the GPU draws. For large vector data, golit.gis.vector_tiles keeps the GeoDataFrame server-side and streams MVT vector tiles (pip install "golit[gis-vector-tiles]") so 100k+ features render without inlining the whole GeoJSON.

import golit.gis as gis

@app.view
def map(regions):                      # regions is a filtered GeoDataFrame
    return gis.geo_map(regions, color="revenue", tooltip=["name", "revenue"])

Raster works too: gis.raster(dataarray) colormaps a georeferenced rioxarray/xarray array (or GeoTIFF) to a MapLibre image layer, gis.rgb(stack, bands=…) renders a multiband raster as a true/false-color satellite composite (pip install "golit[gis-raster]"), and gis.tiles("scene.tif") streams a very large COG as on-demand z/x/y tiles via rio-tiler (pip install "golit[gis-tiles]") — only the visible window crosses the wire. And gis.terrain(dem, "hillshade") runs WhiteboxTools terrain analysis (slope, flow accumulation, …) into a renderable raster (pip install "golit[gis-terrain]"), and gis.ee_layer(image, vis=…) overlays Google Earth Engine imagery as live tiles (pip install "golit[gis-ee]"). Install vector with pip install "golit[gis]" (DuckDB spatial rides on the sql extra). Moving a control re-runs only the filter + map node — the fragment swaps in place on the initial load and after a POST/SSE. See examples/geo_explorer/app.py (vector), examples/vector_tiles/app.py (60k-feature vector tiles), examples/raster_explorer/app.py (raster), examples/rgb_composite/app.py (RGB composite), examples/tiled_raster/app.py (tiled COG), examples/terrain_analysis/app.py (terrain), and examples/earth_engine/app.py (Earth Engine).

Realtime: video and audio

Some views don't re-render on a change — they hold a live connection. golit.ui.chat(channel) opens a WebSocket-backed chat panel (@app.on_message adds bot/moderation logic). For computer vision, @app.stream(name) + ui.webcam(name) push a server-side MJPEG feed the browser plays in a plain <img> — a host camera, a detector drawing boxes, a synthetic animation — and shared=True fans one producer out to many viewers. The mirror, @app.on_frame(name) + ui.camera(name), streams the visitor's own webcam up over a WebSocket, runs your handler on each frame server-side, and paints the annotated result back.

import numpy as np
import golit.ui as ui

@app.on_frame("faces")
def detect(frame: np.ndarray) -> np.ndarray:   # (H, W, 3) uint8 RGB in and out
    ...                                          # run your model, draw boxes
    return frame

@app.view
def live() -> str:
    return ui.camera("faces", title="Your camera")

Frames are JPEG bytes or (H, W, 3) RGB arrays (encoded with Pillow). Sync handlers run in a worker thread; one frame is in flight at a time, so a slow model lowers the rate instead of backing up, and a producer/handler that errors is logged without dropping the stream. pip install "golit[vision]" (or [vision-cv] for OpenCV). See examples/webcam_stream (server feed), examples/browser_camera (browser camera), and examples/face_detect (real OpenCV face detection).

For audio, ui.recorder(name) captures the visitor's mic and uploads each clip as 16-bit WAV (with inline playback + a download link for the clip); the @app.on_audio(name) handler decodes it (Python's stdlib wave — no ffmpeg) and returns a result to show, or audio to play back. See examples/audio_recorder and Audio recording.

Components

Inputs (reactive) — slider, number, select, text, checkbox, upload, radio, multiselect, switch, date, textarea, button.

Display (golit.ui) — card, columns, grid, tabs, expander, accordion, divider, metric, scorecard, alert, badge, progress, skeleton, spinner, table, markdown, code, json_view, heading, caption.

Realtime (golit.ui) — chat, webcam, camera, recorder.

import golit.ui as ui

@app.view
def panel(by_region, total):
    return ui.card(
        ui.columns([ui.metric("Revenue", f"${total:,}", delta="+8%"), chart_fig]),
        title="Overview",
    )

Components compose through the renderer, so any argument can be a DataFrame, a chart figure, another component, or trusted HTML. See examples/components_gallery/app.py.

Page layout

By default views stack under one controls panel. golit.layout arranges the reactive view fragments into a sidebar, rows, tabs, etc. — the layout is static scaffold, so each view keeps its id and still swaps in place on POST/SSE.

from golit import layout as L

app.layout = L.Sidebar(
    L.Controls(),                                  # all inputs, in the sidebar
    L.Stack(
        L.Row(L.View("kpi"), L.View("status")),
        L.Tabs({"Chart": L.View("chart"), "Data": L.View("table")}),
    ),
)

References are validated at build time: every View/Control must resolve to a real view/input and be placed at most once.

Deploying and scaling

A single process needs nothing extra. To scale horizontally, set GOLIT_REDIS_URL and run N single-worker instances behind a sticky (session-cookie) load balancer — session state is worker-local by design, and Redis fans server-side invalidations across the fleet. A runnable podman/nginx stack lives in deploy/.

pip install "golit[redis]"
export GOLIT_REDIS_URL=redis://localhost:6379
golit run examples/sales_explorer/app.py

See DEPLOYMENT.md for the full topology and why uvicorn --workers can't provide session affinity.

Architecture

Tier	Role	Technology
0	Reactive kernel	Rust + PyO3 (src/, golit._golit)
1	Orchestrator	Litestar + SSE/Redis fan-out (golit.server)
2	Transport	HTMX fragments; static SVG, interactive charts, native maps (golit.rendering)
3	Local shield	Alpine.js (widget immediacy, tab state)

See project_scope.md for the full architecture and golit_benchmark.md for the benchmark methodology.

Status

v1.0.0 — first stable release (see the CHANGELOG).

Built end-to-end and green (17 cargo + 209 pytest, ruff + mypy clean): Rust kernel, reactive engine, rendering (static and interactive charts, native MapLibre maps, auto-rendered Great Tables), the golit.ui component library, page layout, DuckDB SQL nodes, GIS (vector maps + MVT vector tiles for large data; single-band, RGB-composite, tiled-COG raster maps; WhiteboxTools terrain; Earth Engine overlays; spatial SQL — golit.gis), Litestar server (POST + SSE), Redis pub/sub fan-out, multi-worker deployment, live polled sources (@app.poll), realtime WebSocket chat, video (server-side MJPEG streams + browser-camera CV), and audio (mic recorder), the benchmark harness (bench/, with measured Golit-vs-Dash results), and the examples.

Deferred: a standard-cloud-instance benchmark publication and the wider design suite in golit_pages/.

Development

make dev      # set up venv + build extension
make test     # cargo test + pytest
make lint     # ruff + mypy
make build    # release wheel

License

Golit is released under the Apache License 2.0. © 2026 Daniel Boadzie.