Open source tool maker Grafana Labs says hackers stole its code, and refuses to pay ransom.

Grafana Labs, the maker of its popular open source web visualization software, confirmed it had been hacked but refused to pay hackers who threatened to release the company’s database.

In a series of posts on social media, the lab said its investigation found that hackers had misused stolen token credentials allowing access to the company’s GitLab environment, which it uses to develop code. The code did not provide access to customer records or financial data, but it did allow hackers to obtain company repositories of source code. The company has since invalidated the token and added additional security measures to prevent a repeat of the incident.

“The attacker attempted to blackmail us, demanding payment to prevent our codebase from being published,” the company said.

Grafana’s code is open source and public, meaning anyone can download the software and modify its code before running it on their own hardware. It is not clear whether the hackers stole any code or private information. A company spokesman did not immediately respond to a request for comment.

The incident contrasts with the recent hack at edtech giant Instructure, which last week “reached an agreement” to pay hackers who breached its network twice in recent weeks. The hackers had demanded an unspecified ransom, and threatened to release stolen data about staff and students using its software after a massive data breach and subsequent website defacement.

While in the case of Grafana, no customer data was taken, the company cited long-standing FBI advice urging victims not to pay hackers, because cooperating with hackers does not guarantee that they will return stolen data or refrain from publishing it later. Critics also say that paying cybercriminals helps fund future cyberattacks.

Grafana said its investigations are continuing and will announce its findings once the investigation is completed.