What Really Happens When Cloudflare D1 Free Tier Hits Its 500 MB Storage Limit

A developer stress-tested Cloudflare D1's free-tier database by filling it to its 500 MB storage cap via the REST API in July 2026 to document exactly what breaks at the limit. The database rejected new writes with an HTTP 400 error code 7500 at precisely 499,994,624 bytes, a threshold enforced at SQLite's 4 KB page granularity, while read operations continued unaffected. Contrary to an initial assumption, small writes do not bypass the wall — they simply consumed the last remaining headroom before the limit was enforced. Recovery is possible immediately by deleting rows, which drops storage usage at once, but the deletion itself counts against the free tier's daily write quota of 100,000 rows. The author also flagged that building an index on a blob column can roughly double storage consumption, potentially pushing a database into the limit on its own.