Invalid Client Credentials Error on OAuth Token Request for NLP Scope

[Avi Bomjan]

Hi everyone,

I'm a developer integrating the FatSecret Platform API into my app, and I'm hitting a snag with authentication.

My app uses client_credentials grant type to get a token for the NLP endpoint. The request is a POST to https://oauth.fatsecret.com/connect/token with scope "nlp", but I get a 400 response:

{ "error": "invalid_client", "error_description": "The client credentials are invalid" }

I've double-checked my credentials match the app dashboard, and the request is formatted as application/x-www-form-urlencoded. My app is set up for Premier with NLP access.

Has anyone else run into this? Is there something specific for NLP scope or client_credentials? Any tips on troubleshooting or if this could be an account config issue?

Thanks in advance for any help!

[seba...@fatsecret.com]

Thanks for reaching out.

Missing Basic Auth Header: You mentioned you formatted the request as application/x-www-form-urlencoded. Assuming you likely included the client_id and client_secret as parameters in the body of the POST request. While some OAuth2 implementations accept this, the fatsecret authentication server expects the credentials to be Base64 encoded and passed in the Authorization header (Basic Auth).

Reg. Premier scopes: When using OAuth2.0, iIf no scope is specified then all scopes you have access to will be sent see https://platform.fatsecret.com/docs/guides/authentication/oauth2

[Avi Bomjan]

Dear FatSecret Support Team,

I'm integrating the NLP endpoint with OAuth 2.0 (client_credentials grant). When requesting 'nlp' scope, I get error: {"error":{"code":"14","message":"Missing scope: scope 'nlp'"}}.

Please enable 'nlp' scope for my account. If premium upgrade or more details needed, let me know.

[seba...@fatsecret.com]

Thanks for reaching out.

NLP is an optional add-on which can activated via a 14 day free trial from your Platform API Account Dashboard and is billed in tiers of 25,000 inputs per month.

[Avi Bomjan]

Dear Seba,

Thank you for the quick and clear explanation — that’s really helpful.

I’d like to go ahead and activate the 14-day free trial for the NLP add-on right away from my Platform API Account Dashboard.

While I’m setting that up, could you please share a bit more detail on the billing once the trial ends? Specifically:

• What are the actual rates for the different tiers (e.g. per 25,000 inputs)?
• How is usage calculated (per successful NLP call, per input, etc.)?
• Are there any minimum commitments or overage charges?

Just to give you context — the app is currently in MVP stage with only one active user at the moment, so volume will be very low to start with. Any guidance on how billing works for early-stage / low-volume usage (or whether we might qualify for any startup discounts) would be greatly appreciated.

Thank you again for your support — really keen to get the NLP endpoint up and running.

Best regards, Avi Bomjan

[seba...@fatsecret.com]

Thanks, you can activate your free trial from your API Account Dashboard: https://platform.fatsecret.com/login

Full pricing is provided there i.e. billing is structured in tiers of 25,000 inputs per month. Every tier is billed at the same monthly amount.