Each of the 371 databases of BioCyc describes the genome and metabolic pathways of a single organism. The BioCyc databases are divided into 3 tiers, based on their quality: Tier 1: 3 Databases, which have been created through intensive manual efforts and receive continuous updating: 1) *EcoCyc* describes the model organism Escherichia coli K-12. 2) *MetaCyc* describes metabolic pathways and enzymes for more than 1,500 organisms. 3) *BOCD* (BioCyc Open Compounds Database) is an open collection of chemical compound data from the BioCyc databases. BOCD includes metabolites, enzyme activators, inhibitors, and cofactors. Tier 2: 20 Databases, which were computationally generated and have undergone moderate curation. Tier 3: 349 Databases, which were also computationally generated, but have undergone no curation. Scientists can use the BioCyc Web site to visualize individual metabolic pathways or to view the complete metabolic map of an organism. The latter diagram can be used to analyze gene expression, proteomics, or metabolomics data, such as to produce animated views of time-course gene-expression experiments. The BioCyc Web site also provides genome browsing capabilities, and for the *EcoCyc* databases in particular, provides extensive information about transcriptional mechanisms of gene regulation.

ChemSpider is a free chemical structure database providing fast text and structure search access to over 32 million structures from hundreds of data sources.

GeoReM is a Max Planck Institute database for reference materials of geological and environmental interest, such as rock powders, synthetic and natural glasses as well as mineral, isotopic, biological, river water and seawater reference materials. It contains published analytical data and compilation values (major and trace element concentrations and mass fractions, radiogenic and stable isotope ratios). GeoReM covers all important metadata about the analytical values such as uncertainty, analytical method and laboratory. Sample information and references are also included. GeoReM contains almost 3,400 reference materials, about 46,200 analyses from almost 10,000 papers, and preferred analytical values (State: November 2017).

The database GEOROC is maintained by the Geoscience Centre at Göttingen University. The database is a comprehensive collection of published analyses of volcanic rocks and mantle xenoliths. It contains major and trace element concentrations, radiogenic and nonradiogenic isotope ratios as well as analytical ages for whole rocks, glasses, minerals and inclusions. Samples come from 11 different geological settings. Metadata include, among others, geographic location with latitude and longitude, rock class and rock type, alteration grade, analytical method, laboratory, reference materials and references.

LIVIVO bundles scientifically relevant resources from the subjects fields medicine, health, nutrition, environmental and agricultural sciences. It provides a common search interface over various data sources, such as library catalogs, specialist bibliographic databases, full texts from journals, and quality-controlled web content. LIVIVO combines the former ZB MED search portals MEDPILOT (2003 to 2015) and GREENPILOT (2009 to 2015).

NMRShiftDB is a web database for organic structures and their nuclear magnetic resonance (nmr) spectra. It allows for spectrum prediction (currently only for carbon) as well as for searching spectra, structures and other properties. Last not least, it features peer-reviewed submission of datasets by its users.

The MPI-Mainz-UV-VIS Spectral Atlas is a comprehensive collection of absorption cross sections for gaseous molecules and radicals, primarily relevant to atmospheric research, from measurements performed during the last nine decades. The individual data sets were collected from the original publications, either copied from tabulations, or read from figures in those cases where numerical data could no longer be obtained. Other sources rely on the internal databases of several research centers dealing with atmospheric chemistry and/or molecular spectroscopy. Numerous excellent high-resolution spectra were obtained from personal communications with the scientists.

Zenodo is an open data repository, developed and operated by CERN. It is an catch-all repository, that welcomes research from all over the world, and from every discipline. Zenodo does not impose any requirements on format, size, access restrictions or licence. A digital object identifier (DOI) is automatically assigned to all Zenodo files and it is integrated into reporting for research funded by the European Commission.