The GPL's conditions are triggered only by distribution. If you distribute modified code, or offer it as a networked service, you must make the source available

The GPL's conditions are triggered only by distribution. If you distribute modified code, or offer it as a networked service, you must make the source available under the same terms. Offering as a networked service is not distribution. That was why they had to make AGPL to put conditions on use in networked services.