> ## Documentation Index > Fetch the complete documentation index at: https://developers.openalex.org/llms.txt > Use this file to discover all available pages before exploring further. # Download Changefiles > Download incremental updates to keep your local data current Changefiles let you download only what's changed since your last snapshot, so you can keep a local copy of OpenAlex up to date without re-downloading the full dataset. Each day's changefile contains every entity that was created or modified on that date. The API keeps the last 60 days of changefiles available. **Downloading daily changefiles requires a paid plan.** The free public snapshot is refreshed **quarterly**. A **daily-refreshed snapshot** and the **daily changefiles** documented on this page (the `/changefiles` API) are only available to subscribers on a [paid plan](https://openalex.org/pricing). Contact [sales@openalex.org](mailto:sales@openalex.org). ## Access and pricing There are two distinct things here, with two different access levels: * **Browsing the changefile list** — the `/changefiles` and `/changefiles/{date}` endpoints below just tell you which dates and files are available. They are **free, unlimited, and require no API key.** Browse them as much as you like to see what's there before you subscribe. * **Downloading the actual data files** — the `content.openalex.org/...` URLs returned in those listings deliver the data, and require an **API key on a paid plan** (Premium, Institutional, or Partner). There's no per-file charge; changefile downloads are included with your plan. See [pricing](https://openalex.org/pricing) or contact [sales@openalex.org](mailto:sales@openalex.org). ## List Available Dates The `/changefiles` endpoint returns all available changefile dates. This is free and needs no API key: ```bash theme={"dark"} curl "https://api.openalex.org/changefiles" ``` ```json theme={"dark"} { "meta": { "count": 9 }, "results": [ { "date": "2026-02-20", "url": "https://api.openalex.org/changefiles/2026-02-20" }, { "date": "2026-02-19", "url": "https://api.openalex.org/changefiles/2026-02-19" }, { "date": "2026-02-18", "url": "https://api.openalex.org/changefiles/2026-02-18" } ] } ``` ## Get a Day's Changes Follow a date's URL to see which entities changed or were created - and how many of each - and download links in both [JSONL](https://jsonlines.org/) and Parquet. This listing is also free and needs no API key: ```bash theme={"dark"} curl "https://api.openalex.org/changefiles/2026-02-19" ``` ```json theme={"dark"} { "meta": { "count": 19, "date": "2026-02-19" }, "results": [ { "entity": "works", "records": 3171968, "formats": { "jsonl": { "size_bytes": 10842055680, "size_display": "10.1 GB", "url": "https://content.openalex.org/changefiles/2026-02-19/works_2026-02-19.jsonl.gz?api_key=YOUR_KEY" }, "parquet": { "size_bytes": 12130148352, "size_display": "11.3 GB", "url": "https://content.openalex.org/changefiles/2026-02-19/works_2026-02-19.parquet?api_key=YOUR_KEY" } } }, { "entity": "authors", "records": 3124690, "formats": { "jsonl": { "size_bytes": 9664790758, "size_display": "9.0 GB", "url": "https://content.openalex.org/changefiles/2026-02-19/authors_2026-02-19.jsonl.gz?api_key=YOUR_KEY" }, "parquet": { "size_bytes": 6938735872, "size_display": "6.5 GB", "url": "https://content.openalex.org/changefiles/2026-02-19/authors_2026-02-19.parquet?api_key=YOUR_KEY" } } }, { "entity": "institutions", "records": 48857, "formats": { "jsonl": { "size_bytes": 95621065, "size_display": "91.2 MB", "url": "https://content.openalex.org/changefiles/2026-02-19/institutions_2026-02-19.jsonl.gz?api_key=YOUR_KEY" }, "parquet": { "size_bytes": 40703645, "size_display": "38.8 MB", "url": "https://content.openalex.org/changefiles/2026-02-19/institutions_2026-02-19.parquet?api_key=YOUR_KEY" } } } ] } ``` Each entry includes: * **entity** — the entity type (works, authors, institutions, etc.) * **records** — total number of created or modified records * **formats** — download URLs and file sizes for JSONL (gzipped) and Parquet ## What's in a Changefile A day's changefile contains every entity record that was **created or modified** on that date. This includes: * Newly created entities (e.g., a paper published today) * Existing entities with updated metadata (e.g., a work that gained new citations) Each record is a complete entity object — the same format you'd get from the API. To apply the update, upsert into your local data using the entity's `id` as the primary key. ## Incremental Update Workflow 1. Note the date of your last full snapshot or changefile download 2. List available changefiles and identify dates after your last update 3. For each new date, download the entity files you need 4. Upsert records into your local copy using `id` as the primary key ```python theme={"dark"} import requests API_KEY = "YOUR_KEY" # 1. List available changefiles dates = requests.get( f"https://api.openalex.org/changefiles?api_key={API_KEY}" ).json()["results"] # 2. Pick dates after your last update last_update = "2026-02-17" new_dates = [d for d in dates if d["date"] > last_update] # 3. Download each day's changes for date_info in new_dates: day = requests.get(date_info["url"]).json() for entity in day["results"]: if entity["entity"] == "works": download_url = entity["formats"]["jsonl"]["url"] print(f"{date_info['date']}: {entity['records']:,} works " f"({entity['formats']['jsonl']['size_display']})") # download and upsert... ``` ## Formats Changefiles are available in two formats: | Format | Extension | Best for | | --------------- | ----------- | ----------------------------------------------------------------- | | JSONL (gzipped) | `.jsonl.gz` | Streaming ingestion, line-by-line processing | | Parquet | `.parquet` | Analytics, loading into data warehouses (BigQuery, Spark, DuckDB) | Both contain the same data — choose whichever fits your pipeline.