ChEMBL Database — Bioactivity Queries

Why no SDK? The chembl_webresource_client package is convenient sugar over a public, no-auth REST/JSON API at https://www.ebi.ac.uk/chembl/api/data/. When the SDK is unavailable, every operation can be reproduced with plain requests and URL parameters. This SKILL.md uses the REST path throughout so the code runs in any environment with requests installed. Django-style filter syntax (field__icontains=…, field__lte=…, field__range=a,b) works as URL query parameters.

Overview

ChEMBL is EMBL-EBI's bioactive molecule database: 2M+ compounds, 19M+ bioactivity measurements (IC50, Ki, EC50, Kd, …), 13K+ targets. The REST API at https://www.ebi.ac.uk/chembl/api/data/ returns JSON (append .json) or XML/YAML, requires no authentication, and supports Django-style query filters via URL parameters plus cursor-style pagination via page_meta.next.

When to Use

• Finding compounds by name, ChEMBL ID, or physicochemical properties
• Querying bioactivity data (IC50, Ki, EC50) for specific targets
• Performing similarity or substructure searches using SMILES
• Retrieving drug mechanisms of action and clinical indications
• Identifying inhibitors, agonists, or bioactive molecules for a target
• Analyzing structure-activity relationships (SAR) across compound series
• Filtering molecules by Lipinski rule-of-5 or other drug-likeness criteria
• For general cheminformatics (SMILES manipulation, fingerprints, descriptors) use rdkit-cheminformatics instead
• For an alternative compound database (NIH, broader coverage) use pubchem-compound-search