Use a public dataset

Datasets lists every public dataset. A dataset’s public page carries its README, tables, freshness, JSON explorer and AI access. Its Use dataset button prints the API, MCP and download instructions.

Create a personal mr_use_… key under Settings → Access and send it against any public dataset. The first keyed request connects that dataset to the workspace, which lists it under Using and counts it as a use for the publisher. The connection copies nothing and leaves the active workspace alone.

Choose how to use the data

Need	What to use
Inspect a small result	Explore data in the app. Your browser uses your signed-in session and never receives an API key.
Ask Claude, Codex, or another agent	Use with AI. Connect the MCP client with OAuth and pick the workspace.
Write an application, notebook, or job	Use the API with an mr_use_… key.
Train a model or refresh a local analytical store	Download the current Parquet file and query it locally with DuckDB, Polars, Pandas, or Arrow.

An mr_use_ key belongs to the member who made it and works in one workspace. It reads any public dataset and that workspace’s own tables, up to 10,000 rows a query, paged to the end. It never reads another workspace’s private tables. A dataset the workspace removed under Using comes back on the next key request for it.

mr_live_… is the subscription key for the SDK and hosted tables. mr_cli_… authorizes a command-line device. Query and Current take only mr_use_….

Query small results as JSON

The query endpoint returns bounded rows, filters, ordering and aggregates as typed JSON. Each answer names the table version and content digest behind the result.

curl -sS \
  -H "x-api-key: $MOSTLYRIGHT_API_KEY" \
  -H "content-type: application/json" \
  -d '{"columns":["city","date","temperature"],"limit":25}' \
  "https://api.mostlyright.md/api/v2/public/tables/$TABLE_ID/query"

The query object is closed, and the endpoint runs no arbitrary SQL. A response reports returned rows, scanned bytes, elapsed time, and whether its row limit cut the result.

Public Dataset API carries the request and error contract.

Download the current Parquet file

Current hands back the complete immutable snapshot.

curl -sS -o table.parquet \
  -H "x-api-key: $MOSTLYRIGHT_API_KEY" \
  "https://api.mostlyright.md/api/v2/public/tables/$TABLE_ID/current"

Every response carries a strong ETag and a SHA-256 content digest. Send that ETag back as If-None-Match on the next refresh. A 304 means the file has not changed, and nothing downloads.

import duckdb

rows = duckdb.sql("""
  select city, avg(temperature) as mean_temperature
  from read_parquet('table.parquet')
  group by city
  order by mean_temperature desc
""").fetchall()

Do not fetch Current on every inference request. Refresh on a schedule, verify the digest, then replace a local file or DuckDB table atomically. The request path queries that copy with predictable latency.

Remove access

Removing a dataset from the workspace stops its Current and Query access at once. Revoking a key stops the requests made with it. Disconnecting an AI tool ends its OAuth connection.