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100 ISBN conversions per month. No credit card required.
Sign Up FreeNo subscription. No monthly fee. No credits that vanish at the end of the month. Pay for the conversions you run, not for the months you don't. Most ISBN tools charge a fixed fee whether you use them or not; ISBNConverter.com charges only when you convert.
ISBN conversion is not a daily task for most people. A cataloguer might need to convert 5,000 ISBNs once a quarter when updating a database export. A librarian might convert a batch of records once and not touch the tool again for months. A developer might test a few dozen codes while building an integration, then convert tens of thousands when the project goes live.
None of these patterns fit a subscription model; you'd spend most of the month paying for access you're not using. Prepaid credits fit. You buy exactly what you need, and use it when you need it.
10,000 credits for $10.00 works out to around $0.001 per conversion. In practice that covers a typical library catalogue record update, an entire publisher backlist migration from ISBN-10 to ISBN-13, a year or more of developer testing and integration work, or most small-to-mid publisher cataloguing projects from start to finish.
Credits don't expire. Use 200 this month and none for the next six; the remaining balance waits with no maintenance fee and no pressure to spend before a deadline.
One credit converts one ISBN code, across any tool: the single converter on the homepage, the bulk converter, the file upload converter, or the REST API. If a code cannot be converted (for example, a "979"-prefixed EAN when converting to ISBN-10) it is left unchanged and no credit is consumed.
Free credits (100 per month) are consumed first. Paid credits are drawn on once the free balance is exhausted. Your total capacity at any moment is the sum of both.
Every account includes 100 free credits per month, reset automatically on the 1st of each month. No credit card required to sign up. That is enough for individual lookups, testing a new workflow, small one-off conversions, and evaluating whether the tool fits your process before committing to anything. When you need more, paid credits are a single purchase away.