# SelectTransform/st.js

JSON template over JSON

Repository: https://github.com/SelectTransform/st.js
Canonical: https://ross.abutalabs.com/products/stjs
Homepage: https://selecttransform.github.io/site/
Language: JavaScript
License: MIT
License Family: permissive
Last push: 2023-01-11T11:18:46+00:00

## Health v2 (maintenance only)
Score: 32/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 35, longevity 100
- inputs: {"age_days": 3257, "days_push": 1330, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1223, forks 61 (observed 2026-08-28T04:04:02.682776+00:00)

## What it is
ST (SelectTransform) is a JavaScript library that lets you query and select subtrees of any JSON object with selector functions, and transform JSON into other JSON using declarative templates written in JSON itself. Select and Transform can be combined for partial transforms and modularizing JSON structures.

## Use cases
- transform one JSON payload into another shape using a JSON template
- find all key/value pairs in a JSON tree matching a filter function
- reshape API responses into a different JSON structure
- extract matching subtrees from deeply nested JSON
- generate HTML snippets from JSON data via each-loops in templates
- modularize and partially transform large JSON objects

## When to choose
- you want declarative JSON-to-JSON transformation without writing imperative mapping code
- you need to query or filter nested JSON structures with custom selector functions
- you prefer templates expressed in JSON rather than a separate template language

## When to avoid
- you need high-performance bulk JSON processing on large datasets
- you want JSON schema validation rather than transformation
- your project needs a actively developed library with frequent updates

## Facets
- artifact type: library
- maturity: maintenance
- function: serialization, parser, templating, developer-tools
- domain: developer-tools, apis
- platform: cross-platform
- tags: -transformation, -templating, -selector, data-mapping, -to-, data-engineering, javascript, nodejs

## Member repositories
- SelectTransform/st.js (main) score 32

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:02.682776+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T06:15:31.009094+00:00, confidence not recorded.
  - readme: https://github.com/SelectTransform/st.js (fetched 2026-08-28T04:04:02.682776+00:00, sha c58957133368)
  - homepage: https://selecttransform.github.io/site/ (fetched 2026-08-29T12:23:36.311476+00:00, sha ff98f00b3a2d)
- Data as of 2026-08-30T08:39:29.467469+00:00.