On Infogreffe you have access to the binding “Certificate of registration” (Extrait Kbis) of a French company or branch office (no other websites provide such a binding certificate for the moment). The Certificate of registration is only a picture of a company on its date of issuance (since the company can be in the course of filing changes that will appear soon after). However, no changes are enforceable against third parties until they are published through Infogreffe. It is thus essential to have a very recent Certificate of registration when any binding effect is needed.
You can also order on Infogreffe a certificate of insolvency proceedings, a status of pledges and inscriptions on the business and certain assets, a history of the corporate changes made to the company, and generally most of the documents filed with the Trade and Companies Registry (annual and consolidated accounts, Articles of Association, mandatorily published shareholder resolutions, auditor reports, documentation linked to mergers, wind-ups, share contributions, etc.). All such company documents are subject to a fee (e.g., a Certificate of registration: €3.37; other corporate documents such as Articles of Association, shareholder minutes, reports: €10.05; a bankruptcy certificate: €4.73; a full status of pledges and inscriptions on the business and certain of its assets: €85.35).
Legal representatives of companies (but only them) can, after creating an account, order the equivalent of a Certificate of registration of their company (free of charge) on the website "MonIdenum": https://monidenum.fr/ (website in French only).
On INPI you can download free of charge all (or most of) the company documents and accounts filed with Infogreffe, so this is an extremely useful way to get free corporate documents in France.
On Pappers, you can also download free of charge all (or most of) the company documents and accounts filed with Infogreffe, so this is an extremely useful way to get free corporate documents in France (however, since it is not the official channel of information, it is always useful to double-check on Infogreffe to see e.g. whether the latest Articles of Association published on Pappers are of the same date as those published on Infogreffe).
Société.com also provides company documents but these are not free of charge.