We present recent developments in the open-source "Firefly" astronomical data access, exploratory analysis, and visualization toolkit. Firefly is the core library from which the NASA IRSA archive web interfaces and the Rubin Science Platform's Portal Aspect are constructed, and is also used in many roles in the NASA Extragalactic Database (NED) and Exoplanet Archive web interfaces.

Firefly is evolving rapidly into a general-purpose tool for exploring astronomical data through IVOA standard data-access protocols. Recent developments have extended Firefly's capabilities in querying observation data in the ObsCore data model, via ObsTAP, and this has allowed the deployment of image-query services for the Rubin Data Preview exercises in a purely standards-based way.

We will also describe extensive new capabilities built around the IVOA DataLink standard. These have allowed providing connections between related datasets, such as the retrieval of light curves or of the image on which a source was observed, in a completely standards-based way that avoids the need for putting mission-specific information into the data-access application. DataLink also allows us to construct query screens for datasets in an entirely metadata-driven way, allowing new query capabilities to be introduced without changes to the front-end application.

We will also present recent enhancements to Firefly that extend its capabilities as an exploratory-data-analysis tool for astronomical images and catalogs.

Firefly is open-source software and a Firefly server is available as a pre-built containerized application, with substantial run-time configurability. We will show how to use the container image to rapidly establish an archive query interface for standards-compliant data services.