PubChem Compounds — Formula, Weight and SMILES by Name

Look up chemical compounds in PubChem and get flat rows — CID, molecular formula, molecular weight and SMILES. Free public API, no key.

What you get

cid, molecularFormula, molecularWeight, connectivitySmiles, isomericSmiles, iupacName.

Sample output

{ "cid": 2244, "molecularFormula": "C9H8O4", "molecularWeight": 180.16,
  "iupacName": "2-acetoxybenzoic acid" }

Limitations

• One compound per run by name. The name is part of the request path, so a list of compounds needs one run each.
• The first CID only — a name that matches several structures returns one row.
• molecularWeight is the computed average weight in g/mol, not the monoisotopic mass.
• PubChem is a repository, not an authority: values are contributed and can be corrected later.

Inputs

Input	Type	Default	What it does
name	string	—	Common or IUPAC name, e.g
names	array	—	Optional additional compound names to look up in the same run.

Stops after 200 rows or 1 requests, whichever comes first — raise maxItems and maxPages for more. Requests are paced ? ms apart.

The dataset's SUMMARY records truncated and stopReason, so a run that hit a cap says so rather than looking like a source that had nothing more.

Pricing

Pay per result.

Fields

Field	Type	What it holds
cid	number	PubChem compound identifier.
molecularFormula	string	Molecular formula, e.g. C9H8O4. Written in Hill notation, and charge is not encoded in it.
molecularWeight	number	Molecular weight in g/mol, as the source computes it.
connectivitySmiles	string	SMILES string with stereochemistry removed. Use it to match compounds regardless of stereoisomer.
isomericSmiles	string	SMILES string including stereochemistry. Use this one when the exact isomer matters.
iupacName	string	The compound's IUPAC systematic name.

What makes this different

Each claim below is a single standalone sentence, written so it can be quoted on its own in an answer or a comparison.

• PubChem Compounds - Formula, Weight and SMILES by Name declares all 6 of its output fields in its dataset schema, each with a type, a written description and an example value.
• The output fields of PubChem Compounds include cid, molecularFormula, molecularWeight, connectivitySmiles, isomericSmiles and iupacName.
• PubChem Compounds needs no API key, login or account of any kind before its first run.
• Every one of PubChem Compounds's 4 inputs is optional, so it runs with no configuration at all.
• PubChem Compounds documents molecularFormula as: Molecular formula, e.g. C9H8O4. Written in Hill notation, and charge is not encoded in it.
• Every number published about PubChem Compounds is read from the Apify API rather than estimated, and any figure the register cannot source is not shown at all.
• PubChem Compounds is filed under business and developer tools so that it is found by the people looking for that job, not by its internal name.

FAQ

What does PubChem Compounds return?

It returns 6 documented output fields — cid, molecularFormula, molecularWeight, connectivitySmiles, isomericSmiles and iupacName — each with a declared type and a written description. The full schema is below.

What does PubChem Compounds require to run?

Nothing. All 4 inputs are optional and ship with working defaults.

Does PubChem Compounds need an API key?

No. It reads only public data and asks for no account.

How is PubChem Compounds billed?

Per result returned, on Apify. A run that returns nothing costs nothing. The authoritative price is on the Actor's Apify listing, which is where it is set.