# How to Backfill CS2 Price Data Without Gaps

> Backfill CS2 price data by requesting adjacent UTC ranges from `POST /v1/prices/history`, storing the returned normalized boundaries, and preserving hours where a source has no observation.

Two kinds of gaps need different treatment. A request gap means part of the intended date range was never queried. An observation gap means the range was queried but the selected marketplace returned no data in that bucket. Only the first is a backfill failure.

## Historical coverage available for a backfill

`POST /v1/prices/history` contains continuously recorded marketplace quote OHLC since December 24, 2025. It supports all six sources, although field coverage differs: Skinport is ask-only, CSFloat bid history begins July 18, 2026, and CSFloat and C5Game do not carry `bid_volume`.

| Interval | Maximum range per request |
| --- | --- |
| `5m` | 14 days |
| `30m` | 90 days |
| `1h` | 365 days |
| `1d` | Unlimited |

Each source object includes OHLC prices, last-observed volumes, `sample_count`, and actual `open_time` and `close_time`. The top-level `bucket` is the aligned UTC boundary, not the time of the first observation.

For earlier coverage, `POST /v1/archive/history` provides `1h` and `1d` archive rows from 2023. That archive has a different data model: last-observed prices and order volumes, plus `hourly_volume` and `total_supply` on the `aggregate` source. It should remain a labeled series instead of being silently spliced into OHLC.

## How to plan adjacent requests

Choose one interval, source set, and exact list of `market_hash_name` values. Split the desired range at UTC interval boundaries so the next request starts at the prior response's effective `end`. Persist the response's normalized `start`, `end`, and `interval` with each chunk, then deduplicate by item, source, and `bucket`.

Both history endpoints accept up to 100 items per request and can return successful items beside item-level `errors[]`. Process the successful `items` map even when errors are present, and retry only request-wide transient failures.

## Applicable endpoints

| Endpoint | Returns | Plans |
| --- | --- | --- |
| `POST /v1/prices/history` | Quote OHLC from December 24, 2025; CSFloat bids from July 18, 2026 | Scale, Enterprise |
| `POST /v1/archive/history` | Long-term prices, supply, and sale volume from 2023 | Scale, Enterprise |

## Gap rules

- A valid item with no OHLC buckets in a requested range is omitted from `items`. Keep that interval missing; zero-fill would create a nonexistent price.
- Forward-filling converts observations into a derived last-known series. Label and store that derived series separately if the application needs it.
- A `1h` OHLC request cannot exceed 365 days even though `1d` is unlimited. Chunking does not extend the history start date.
- Archive history updates once or twice per day, so a just-finished archive bucket may not be complete when the backfill runs.

The [multi-year history guide](/resources/how-to-export-multi-year-cs2-price-history) covers the archive fields that should remain distinct from current-price OHLC.