Why podcast SEO vendor due diligence starts with their data sources

What to take away

Apple's published feed requirements still set the baselineartwork, title, description and enclosure tags must all validate before any vendor claims about discovery mean much.
Ask every vendor to name the audience data behind their pitch, then check whether that source is public, licensed or simply asserted.
Programmatic audio buyers should read the IAB UK guide to understand what inventory claims actually cover.
Put the checks in writing before procurement, not after onboarding.

Start with the data behind the pitch

Before judging a discovery promise, ask the vendor to identify the source of every audience figure. Examples include Apple Podcasts Analytics and Spotify for Podcasters; Podtrac and Triton Digital; Chartable when historic reports are cited; and research providers such as Edison Research, Nielsen, Comscore, Ipsos and YouGov.

Classify the evidence: a public RSS feed or specification shows what is published, not audience size; an authorised platform dashboard or licensed report is traceable evidence; an estimate without a named report, access or permission is asserted. Request the report or dated export, its methodology and written permission covering the vendor’s access and reporting to you. Confirm the permission with the data owner and check that its terms cover the intended use.

Why the feed still matters

A vendor can promise better discovery, but the discovery surface has rules. Apple publishes submission guidelines and RSS specifications; use Apple's documentation to check the current requirements, with this Apple Podcasts overview as background. A supplier that has not read Apple's requirements is guessing about your show.

Feed check before pitch

Ask for intended feed URL
Compare against Apple RSS requirements
Validate the feed
Fail: distribution suppressed
Pass: review proposal further

Start by asking for the feed URL they intend to work with, then compare it line by line against the Podcast RSS feed requirements Apple sets out for creators. Check the channel title, description and artwork; for each episode, check its title, description, GUID and publication date, and an enclosure with the media URL, file length and media type. Validate the feed in Apple Podcasts Connect and keep the result; a feed validator can also flag structural errors, but technical validity does not verify audience claims.

If the feed fails validation, nothing else in the proposal matters. A missing episode GUID or an oversized image can suppress distribution regardless of how much metadata work is promised.

Map the data each vendor relies on

Most pitches quote audience numbers. Ask which panel, platform dashboard or licensed dataset produced each figure, whether the vendor has written permission to use it, and what metric and reporting period it represents. Downloads, platform listeners, survey-based reach and attribution are different measures, so record the source's methodology before comparing figures.

Apple Podcasts Analytics and Spotify for Podcasters report on the platform and account covered; ask for an authorised, dated export. For Podtrac, Triton Digital or historic Chartable reports, check the stated measurement or attribution method. Reports from Edison Research, Nielsen, Comscore, Ipsos and YouGov may use research or panel methods, so check the methodology rather than treating an estimate as a download count. The Podcast SEO best tools: data and sources breakdown sets out what each source can and cannot tell you; use those distinctions when assessing a vendor's figures.

Check the advertising claims separately

If the proposal includes monetisation or sponsored placements, the vocabulary changes. Programmatic audio has its own buying conventions, and the Back to Basics Guide to Programmatic from IAB UK explains how inventory is described and traded. For podcast download measurement, compare the vendor's methodology with the IAB Tech Lab Podcast Measurement Guidelines. For UK sponsored content, check the Advertising Standards Authority (ASA) and the CAP Code as well.

A supplier who cannot explain the difference between direct and programmatic audio placement is unlikely to report either one accurately.

Verify radio and listening comparisons

Some vendors benchmark podcasts against radio listening. That data is not freely published. RAJAR's subscriber login sits behind a licence, so ask the vendor for current licence or written permission, identify which data and client uses it covers, and verify access with RAJAR rather than relying on second-hand summaries.

Quoting a licensed dataset without a licence is a commercial risk you inherit as the client.

The due diligence checklist

Confirm the feed validates against Apple's published requirements and that the vendor has documented the check.
Ask for the named source of every audience figure in the proposal, with its date.
Confirm whether the vendor holds a current licence for any panel data it quotes.
Request two references from clients with a comparable show size, and call them.
Check the contract covers who owns metadata changes and feed edits after handover.
Confirm the reporting cadence and which metrics appear in each report.
Ask how the vendor handles a platform policy change mid-contract.
Establish the exit terms, including feed access and historical reporting.
Check sponsored-content labelling against ASA guidance and the CAP Code, and establish who is contractually responsible for compliance.
Confirm the vendor's own site and case studies are accurate about work they personally delivered.

What to read before you shortlist

The Podcast SEO: tools and supplier guide for 2027 covers how the supplier market is structured, which helps you decide whether you need an agency, a freelancer or an in-house hire.

Bring the checklist to every discovery call. A vendor who answers the feed question quickly and names their data sources is usually the one worth a second meeting.

Common questions

How long should due diligence take?

For a single show, two to three weeks is realistic if you verify feed compliance and data sources yourself. Larger catalogues take longer because feed checks multiply.

Do I need a contract clause about data sources?

Yes. Ask the vendor to list the datasets used in reporting and provide written evidence that they hold the necessary rights, including permission to report the data to you. That protects you if a claim is later challenged.

Is a cheap vendor worth the risk?

Price alone tells you little. A lower fee with unverified audience data can cost more than a higher fee with named sources and a documented feed process.

What if the vendor refuses to share their sources?

Treat that as a red flag. Public specifications and licensed datasets can both be described without disclosing commercial secrets.