There are recognized ‘brands’ of certification authorities that may you offer proof of your knowledge, for example ISTQB/BCS (former ISEB). They have many different levels and often employers may state they desire at least Foundation level certificate from job seekers.
Nonetheless, there are another provides, yet your local Software Testing Qualification Board or community may have different programms.
I have collected links to the most known certification authorities and local boards. Hope, this can be helpful someone.
- http://certifications.bcs.org/category/15568 — ISTQB-BCS (ISEB) Certification from UK Software Testing board. There is a several different levels of certification — Foundation, Intermediate, Advanced, Agile Testing
- http://www.brainbench.com/xml/bb/common/testcenter/taketest.xml?testId=473 — Designed for experienced software testers, this test covers the following topics: Dynamic Techniques, Fundamentals, Levels, Management, Monitoring, Static Techniques, Tools, Types.
- http://en.gasq.org/ — Global Association for Software Quality — numerous kinds of software testers certification (REQB, ISTQB, IBUQ, IBAQB, IBITGQ, etc.)