The Syrian government "executed" Syrian-Palestinian web developer and cyberactivist Bassel Khartabil in 2015, his wife has said.

NOURA GHAZI SAFADI ON HER HUSBAND'S DEATH I can't get the words out of my mouth. Today I announce in my name, the name of Basil's family and my family, the confirmation that the order to execute my husband Basel Khartabil was carried out days after he was moved to the Adra prison in October 2015 - an appropriate end for a hero like him. Thank you all for killing my loved one. Thank you all, it is because of you that I was a bride of the revolution, and it is because of you that I have become a widow. Oh, Syria's loss Oh, Palestine's loss Oh, my loss

"I cannot get the words out of my mouth," Noura Ghazi Safadi wrote in a Facebook post late on Tuesday.

"Today, I announce in my name, the name of Bassel's family and my family, the confirmation that the order to execute my husband Bassel Khartabil was carried out days after he was moved to the Adra prison in October 2015."

She did not indicate how she was able to confirm his death.

The computer engineer, also known as Bassel Sadafi and credited with "vastly extending online access and knowledge to the Syrian people", was detained on the first anniversary of the 2011 uprising in Syria.

He was routinely denied access to his family and lawyers, rights groups and his wife said.

He disappeared from official records in October 2015 when he was transferred from the Adra prison in northeast Damascus.

'Better because of Bassel's work'

Khartabil was hailed for his contributions to the open web.

He was the co-founder of Damascus' Aiki Lab, a collaborative online community in Syria, was a regular contributor to Wikipedia, and worked as the Syria lead for Creative Commons, an organisation that aims to make creative content available for others to legally share and build upon.

"We are deeply saddened and completely outraged to learn today that our friend and colleague Bassel Khartabil has been executed by the Syrian regime," Creative Commons said in a statement on Tuesday.

"Creative Commons, and the global commons of art, history, and knowledge, are stronger because of Bassel's contributions, and our community is better because of his work and his friendship."

READ MORE: Concerns over fate of Syrian prisoner

In 2012, Khartabil was named by Foreign Policy magazine as one of top 100 thinkers for "fostering an open-source community in a country long on the margins of the internet's youth culture".

The magazine added that as a computer engineer living in Damascus, his "innovative programming skills helped integrate Syria into the online community".

Many online, including the founder of Wikipedia, expressed outrage over the news of his death, with some vowing to keep his work and "memory alive".

I am saddened and outraged in equal measure. https://t.co/1MzrM49C9t — Jimmy Wales (@jimmy_wales) August 1, 2017

Bassel was an amazing Syrian activist for free knowledge: https://t.co/7kc1SCHxUp



His death is an outrage and a tragedy. https://t.co/ZZEvZBlkDY — Kat Walsh (@mindspillage) August 1, 2017

One way his supporters hope to memorialise Khartabil's work is through the New Palmyra project.

Khartabil launched the project in 2005 and worked with a team of artists in Damascus to remodel the ruins until his arrest nearly eight years later.

Their work became even more important when the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group took control of Palmyra, first in 2015, and then again in late 2016, destroying parts of the treasured ruins.

In April, Creative Commons, along with a US-based 3D printing company, created a 90kg 3D rendering of one of Palmyra's Tetrapylons.

Gigabot at work at #ccsummit. And this is a 3D printed replica of the Tetrapylon. #NEWPALMYRA #freebassel pic.twitter.com/vJmYISGEva — nikki forebber (@antischokke) April 28, 2017

"Khartabil’s visionary work ignited a community that stands for transparency, openness, and free culture and continues to grow via the remix, reuse, and sharing of his foundational work," Creative Commons said in April.

Forced disappearances

Rights groups have said the arrest of Khartabil highlighted how the Syian government has arbitrarily detained and forcibly disappeared thousands of Syrians.

Dana Trometer, the spokeswoman of the #FreeBassel campaign, said it was a "truly sad day".

"He had a high profile in the open-source network in the world," Trometer told Al Jazeera. "But he is not the only one sitting in jail or [involved in any] other kidnapping situation at the moment.

"We can't understand why these good people disappear."

Since the war began in March 2011, there have been more than 106,000 arbitrary arrests, according to the Syrian Network for Human Rights.

As of July 2016, more than 65,000 people have forcibly disappeared, the group documented.

According to Human Rights Watch, tens of thousands of political activists have been detained in Syria and held "solely on the basis of their peaceful activity".