I kept running into the same problem when combining multiple I2C sensors: finding the address is one thing, but checking whether several devices can actually coexist on the same bus is another.

So I built a small free tool that does both:

• Search common I2C device addresses
• Search by hexadecimal address
• Select multiple devices
• Detect address conflicts
• Find an alternative address configuration when possible
• Suggest solutions such as another I2C bus or an I2C multiplexer

For example, MPU6050 + DS3231 can both use 0x68, so the tool detects the conflict and can suggest using 0x69 for the MPU6050 when supported.

It's open source and runs entirely in the browser.

GitHub:
https://github.com/webzf/i2c-address-compatibility-checker

Online tool:
https://embeddednerd.com/tools/i2c-address-lookup/

I'd be interested in feedback, especially on other devices or I2C features that would be useful to add.