# Spent sats (blockspace.to)

blockspace.to is an ord explorer and indexer that also keeps the sat ranges of spent outputs. What that adds, what uses it, and the live state of its index.

URL: https://blockspace.wiki/concepts/spent-sats/

blockspace.to's line on the project list is the owner's: "Tracks spent sats. A Blockspace Labs product." blockspacelabs.com describes it as "an ord explorer and indexer that also tracks which sats have been spent", running a fork of [ord](https://blockspace.wiki/glossary/ord/) with `--index-spent-sats`. The project list marks it live since 2026-10-20 08:32 UTC, when the owner moved its nameservers. This page covers what [spent sats](https://blockspace.wiki/glossary/spent-sats/) are in Blockspace Holdings' documents, what uses them, and the live state of the index.

## What the fork keeps

A BTI record of 2026-08-16 gives the test: on Blockspace Holdings' ord server, asking ord's `/output/<txid>:<vout>` for a spent outpoint returned `spent: True` with `sat_ranges` populated, "that only works with `--index-spent-sats`". The ranges are kept on a 16 TB hard disk; on 2026-08-16 the file was 6.6 TB and append-only.

As of 2026-10-20 the service is "ord server + indexer (spent-sats fork)", on mainnet.

## What uses it

The same ord server is a source for [BTI](https://blockspace.wiki/glossary/bti/). The indexers table lists the spent-sats ord fork as the source the ord adapter adapts, with **definitional** trust. It supplies the binding of inscriptions to sats, sat numbering and inscription numbers, and serves as the audit oracle for BTI's runes decoder and for CAT-21's claimant lookups. See [claims](/concepts/claims-t2/).

The same record names what needs the spent ranges in particular:

- **CAT-21 needs it, unavoidably.** A CAT-21 token is a sat (the first sat of output 0 of the mint), and the cat21 module makes one ord sat lookup per mint, 63,749 mints in all.
- **Inscriptions do not need it in normal operation.** BTI's inscriptions module reaches the spent ranges only through its verification probe, which resolves a sample of inscriptions two ways, ord's binding against its own offset arithmetic, and reports how many agree.

Its conclusion: an ord without `--index-spent-sats` can serve inscription-to-sat binding, but cannot serve CAT-21 and cannot run the verification probe.

## Live state

ord's own status page (as of block 972,320, 2026-10-20 12:17:53 UTC):

| | |
|---|---|
| inscriptions | 128,170,184 |
| blessed | 127,698,141 |
| cursed | 472,043 |
| runes | 216,423 |
| lost sats | 2,895,844,904 |

## Research on it

blockspacelabs.com lists two research studies that would use the spent-sats data. Both are described studies, with no results published:

- **Inscription permanence**: how often inscribed sats are spent or move, and where they go, from blockspace.to's spent sats and the holders appendix's record of sat moves.
- **Lost sats**: the [lost sats](https://blockspace.wiki/glossary/lost-sats/) that coinbase transactions never claimed, so they exist in no output; where and when they were lost.

## Related

How BTI and the holders appendix follow sats is on [sats and ordinals](/concepts/sats-and-ordinals/) and [holders](/concepts/holders/). The inscriptions the explorer shows are covered in [inscriptions](/concepts/inscriptions/).

Sources:

- Blockspace Holdings records
- The blockspacelabs.com page (index.html) · https://blockspacelabs.com
- The project list at block.space/projects · https://block.space/projects
- ord /status (the blockspace.to ord server) · https://blockspace.to/status

Live figures: ord as of block 972,320, 2026-10-20 12:17:53 UTC

Updated: 2026-10-20