Python client for the OmniPath molecular biology prior-knowledge web API.

• One-call lookup() and related() helpers that resolve free-text queries, fetch the matching entities/relations, and pivot identifiers into named columns — no manual primary-key juggling
• Friendly id-type aliases (name, chebi, hmdb, uniprot, genesymbol, kegg, …) and participant-type aliases (protein, small_molecule, …) that hide the MI/OM ontology codes
• Lower-level primitives: export entities, relations, and annotations as DataFrames; resolve free-text identifiers; slice with paging
• Ontology term lookup, search, and hierarchy trees
• Multi-backend output: polars (default), pandas, or pyarrow
• Optional graph conversion to annnet objects
• Query validation against the API schema
• Caching via download-manager, with a fresh() context manager for first-touch refresh

pip install omnipath-client

With polars (recommended default backend):

pip install omnipath-client polars

The two high-level helpers, lookup() and related(), cover most use cases in a single call:

import omnipath_client as op

# Resolve names and pivot identifiers into named columns
op.lookup(
    ['caffeine', 'metformin', 'TP53'],
    id_types=['name', 'chebi', 'hmdb', 'uniprot', 'genesymbol'],
)

# Compounds reported in strawberry (FooDB), as a wide joined table
op.related(
    subject='Strawberry',
    sources=['foodb'],
    id_types=['name', 'chebi', 'hmdb'],
)

# Drug targets for caffeine (positional arg matches either side)
op.related(
    'caffeine',
    sources=['bindingdb'],
    id_types=['name', 'uniprot', 'genesymbol'],
)

# Pathway members from WikiPathways and Reactome at once
op.related(
    object=['WP253', 'R-HSA-70171'],
    sources=['wikipathways', 'reactome'],
    relation_categories=['annotation'],
    id_types=['name', 'uniprot', 'chebi'],
    group_by='object_name',
)

The lower-level primitives are still available for paged scans, raw parquet, or graph export:

# All relations as a polars DataFrame
df = op.relations()

# Resolve free-text identifiers to entity primary keys
op.resolve(['caffeine', 'TP53'])

# Human entities
df = op.entities(taxonomy_ids=['9606'])

# Relations as an annnet graph
g = op.relations(as_graph=True)

# Ontology term lookup
result = op.ontology_terms(['GO:0006915', 'MI:0326'])

# Choose a different backend
df = op.entities(backend='pandas')

Cache control:

# Force a one-shot refresh for everything touched in the block
with op.fresh():
    df = op.related('caffeine', sources=['bindingdb'])

# Wipe the entire on-disk cache (e.g. after a server redeploy)
op.cache_clear()

For more examples, see the quickstart guide.

The client provides access to the OmniPath Utils service for ID translation, taxonomy, and orthology:

from omnipath_client.utils import (
    map_name,           # translate identifiers
    translate_column,   # translate DataFrame columns
    ensure_ncbi_tax_id, # resolve organism names
    orthology_translate, # cross-species translation
)

# Gene symbol to UniProt
map_name('TP53', 'genesymbol', 'uniprot')  # {'P04637'}

# Organism resolution
ensure_ncbi_tax_id('mouse')  # 10090

# Cross-species translation
orthology_translate(['TP53'], source=9606, target=10090)
# {'TP53': {'Trp53'}}

Full API: utils.omnipathdb.org

Full documentation: saezlab.github.io/omnipath-client

The data served by OmniPath is combined from many original resources, each with their own license terms. The OmniPath client software is BSD-3-Clause, but the data is subject to the licenses of the original sources. Some resources restrict commercial use. Tools and documentation for managing license-based access control will be provided in a future release.

If you use OmniPath in your research, please cite:

Türei D, Schaul J, Palacio-Escat N, Bohár B, Bai Y, Ceccarelli F, Çevrim E, Daley M, Darcan M, Dimitrov D, Doğan T, Domingo-Fernández D, Dugourd A, Gábor A, Gul L, Hall BA, Hoyt CT, Ivanova O, Klein M, Lawrence T, Mañanes D, Módos D, Müller-Dott S, Ölbei M, Schmidt C, Şen B, Theis FJ, Ünlü A, Ulusoy E, Valdeolivas A, Korcsmáros T, Saez-Rodriguez J. (2026) OmniPath: integrated knowledgebase for multi-omics analysis. Nucleic Acids Research 54(D1):D652-D660. doi:10.1093/nar/gkaf1126

The client software is licensed under BSD-3-Clause. See Data licensing above for information about the data.