Is the NIST Chemistry WebBook Data Reliable and Free to Use?
The NIST Chemistry WebBook (SRD 69) is a citable, government-compiled reference database, and as of the site's own statements it is accessible without a login or stated fee. Two caveats matter for research use: NIST explicitly makes no warranties about the data, and it reserves the right to charge for access in the future. So the practical answer is: reliable enough to cite as a standard reference source, but verify critical values against primary literature, and don't assume permanent free access.
What backs the data's reliability
The WebBook is not a wiki or a scraped aggregation. According to the site, it provides access to data "compiled and distributed by NIST under the Standard Reference Data Program." That program is the same framework behind NIST's other Standard Reference Data products, and the site states that NIST "uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment."
In practice this means:
- Data are curated and attributed rather than user-submitted.
- Coverage is broad and specific enough to cross-check: over 7,000 organic and small inorganic compounds with thermochemical data, over 8,000 reactions with reaction thermochemistry, and spectral collections ranging from 1,600 UV/Vis spectra to 33,000 mass spectra.
- Each entry typically links to its literature source, which is what you actually cite in a paper.
The warranty limitation, stated plainly
The same page adds that NIST "makes no warranties to that effect, and NIST shall not be liable for any damage that may result from errors or omissions in the Database." This is standard for reference data: the compilation is authoritative, but it is not a guarantee for any specific value. For a publication-grade number — a formation enthalpy, a phase transition temperature — treat the WebBook as your entry point and follow the cited source.
Is it free to use?
The site does not present a paywall, subscription, or payment platform, and no pricing is listed. However, the WebBook states that "NIST reserves the right to charge for access to this database in the future." Two things follow:
- Today: you can search and retrieve data without a stated fee.
- Going forward: free access is not contractually guaranteed. If you build a workflow or a teaching resource that depends on the WebBook, don't hard-code an assumption of zero cost indefinitely.
Copyright is governed by the Standard Reference Data Act, and the site notes that copyright for NIST Standard Reference Data is governed by that Act. If you plan to redistribute substantial portions of the data — rather than cite it — check the terms rather than assuming open reuse.
What you can look up
| Data type | Coverage stated on the site |
|---|---|
| Thermochemical data | 7,000+ organic and small inorganic compounds |
| Reaction thermochemistry | 8,000+ reactions |
| IR spectra | 16,000+ compounds |
| Mass spectra | 33,000+ compounds |
| UV/Vis spectra | 1,600+ compounds |
| Gas chromatography data | 27,000+ compounds |
| Electronic and vibrational spectra | 5,000+ compounds |
| Diatomic molecule constants | 600+ compounds |
| Ion energetics | 16,000+ compounds |
| Thermophysical properties | 74 fluids |
Thermophysical properties for the 74 fluids include density, specific volume, Cp, Cv, enthalpy, internal energy, entropy, viscosity, thermal conductivity, the Joule-Thomson coefficient, surface tension (saturation curve only), and sound speed.
How to find a specific value
You can search by name, chemical formula, CAS registry number, molecular weight, chemical structure, or selected ion energetics and spectral properties. A workable sequence:
- Enter the compound by name or CAS number — CAS is the least ambiguous if the name has variants.
- Open the compound's page and select the data category you need (e.g., "Gas phase thermochemistry data").
- Read the value together with its stated method and reference, and note the reference for citation.
- If the number is central to your result, pull the cited primary source and confirm.
Expected result: a value with an accompanying literature reference, not a bare number. If a category is missing for your compound, that reflects the compilation's coverage, not an error.
Common sticking points
- "No data found" for a valid compound. Coverage is selective; a compound may appear for spectra but not thermochemistry.
- Conflicting values across sources. The WebBook often lists multiple determinations. The choice among them is a scientific judgment you have to make and defend.
- Citing the WebBook vs. the original paper. For most journals, cite the primary source the WebBook points to; cite the WebBook itself when you are referring to the compilation.
- Assuming permanent free access. The future-charging reservation is explicit, so avoid dependencies that can't tolerate a change.