Cross-Database Materials Search

The Fragmentation Problem in Computational Materials Data Materials Project, AFLOW, OQMD, and JARVIS-DFT each expose different APIs, different schemas, and different filter syntaxes. Querying all four for the same material requires four browser tabs, four query languages, and a spreadsheet to reconcile the results. That spreadsheet loses context fast. Which provider returned this formation energy value? What query produced this row? When was it fetched? Copy-paste between tabs strips that information silently, and you only notice when a reviewer asks for your data sources six months later. ...

The OPTIMADE ecosystem looks different in 2026 than it did two years ago. Materials Project finished its r2SCAN migration. Alexandria added millions of new structures. Several smaller providers went offline; new ones came online. Most comparison resources date from 2022–2023. The r2SCAN migration alone changes which MP values you should trust. Follow an old tutorial and you may end up filtering on the wrong thermo endpoint. This directory covers every active OPTIMADE provider as of early 2026: entry counts, functionals, primary data types, compliance level, and the specific workflows each one handles well. ...