MyIdentifiers
Depends
Confidence: Medium
If you're self-publishing wide in the US, Bowker is the only official ISBN source, so you have no real alternative.
New check
Comparison
MyIdentifiers vs 404
MyIdentifiers and 404 both land on Depends.
404
Depends
Confidence: Low
Indie authors who want Amazon's store, print-on-demand, and Kindle Unlimited payouts use KDP, and publishing is free to start.
| Compare | 404 | |
|---|---|---|
| Verdict | Depends | Depends |
| Best for | Self-publishers going wide beyond Amazon | Indie authors self-publishing ebooks and paperbacks |
| Who it's not for | Amazon-only authors. KDP's free ISBN is fine | Authors who want Apple, Kobo, and library sales in one dashboard |
| Privacy | Suffered a 2018 breach with stolen card data; site now advertises industry-standard encryption but has no public security page.⁵ | No known public vulnerabilities found in the sources reviewed.10 |
| Support quality | No direct evidence either way | No support evidence found. |
| Public sentiment | Self-publishers treat Bowker as a necessary evil: the only official US ISBN source, but clunky and overpriced.³ | Retrieved review and forum sources discuss other products named '404', not this product. |
| Biggest gotcha | Card data was stolen in the 2018 breach; monitor statements if you buy.⁶ | Guess: KDP Select requires 90-day Amazon exclusivity for Kindle Unlimited royalties.⁹ |
Pick MyIdentifiers when
- Self-publishers going wide beyond Amazon
- Small presses wanting their own imprint ISBNs
- US authors needing portable, publisher-owned ISBNs
When MyIdentifiers is not a fit
- Amazon-only authors. KDP's free ISBN is fine
- Non-US authors, use your own national ISBN agency
- Anyone expecting a polished, modern web experience
- Bulk buyers shopping on price, there's no competition here
Pick 404 when
- Indie authors self-publishing ebooks and paperbacks
- Writers seeking Kindle Unlimited page-read income
- First-time authors testing a book with zero upfront cost
- Authors wanting print-on-demand without inventory
When 404 is not a fit
- Authors who want Apple, Kobo, and library sales in one dashboard
- Writers unwilling to give Amazon 90-day exclusivity for Kindle Unlimited
- Publishers wanting editing, cover design, or marketing services
- Anyone shopping for a store or CRM: KDP publishes books, not software
Sources
- Bowker | Identifier Services (official site)myidentifiers.comofficial
- Buy ISBNs | Bowkermyidentifiers.comofficial
review
- MyIdentifiers ratings . WorthEPennymyidentifiers.worthepenny.comreview
- Bowker Investigating Breach of ISBN Site . Publishers Weeklypublishersweekly.comsecurity
- Bowker's ISBN Site Has Been Hacked . The Digital Readerthe-digital-reader.comsecurity
- Buying ISBNs from Bowker vs free KDP ISBNmembers.upcs.comreview
- The Bowker ISBN Monopoly . Mediummedium.datadriveninvestor.comreview
- Amazon KDP homepagekdp.amazon.comofficial
- Product security pagekdp.amazon.comofficial
