After escaping Mariupol last month, Dmitry Cherepanov built a website to help people like him get information about loved ones who had stayed behind or fled to another city or country.
Only about a quarter of the Ukrainian port city's pre-war population of more than 400,000 remain there after weeks of shelling and fighting.
Meanwhile, the city council says more than 20,000 civilians have been killed.
Heavy bombardment knocked out Mariupol's utilities soon after the start of Russia's invasion on February 24, so those desperate for news of loved ones have no idea if they are among the dead or still in the city, unable to make contact.
Mr Cherepanov, who is a web developer and ran a retro computer museum in Mariupol, developed the website MRPL.Life with his friend Vladimir Bezuglov.
Mr Cherepanov launched the site on April 13 after settling in the city of Kamianets-Podilskyi in western Ukraine with his wife and children.
People can use it to post photos and information about those they are looking for, in the hope that someone with news will send them a message.
They can also make a post about themselves to let loved ones know they are OK, or about someone who has been confirmed to have died.
"I posted information about my father and soon found out that he had left for Russia. A friend wrote to me," Mr Cherepanov told the ABC.
He said the friend then posted about another mate and found out they had died.
It was too early to say whether the site was really effective, Mr Cherepanov said, but it should be able to help people learn more about those they were looking for.
"In any case, we hope so," he said.
'Please, help find Grandma'
Two weeks after going live, the site already has more than 1,000 posts seeking information about missing people, with more being added every day.
Most feature photos from happier times: an older woman sitting at a kitchen table in a pink head scarf, a couple posing against a railing with the sea in the background, a smiling young woman in a fur-collared coat posing for a filtered selfie.
"Please, help find Grandma!" one pleads, alongside a photo of a woman on a playground swing.
Another has a photo of a family of five with a Christmas tree and reveals they were last heard from on March 2 when they were staying in a basement with another family.
One poster is looking for someone's uncle, Alexander:
Marina Aleinik, who made it to Germany with her mother and daughter after escaping Mariupol in mid-March, posted on the site seeking information about her aunt, Victoria.
"With my aunt, we were not close but we were in touch every day when the war started," she told the ABC.
"The last call I made to her was on the second of March. Next day we lost mobile connection."
Ms Aleinik said she was relieved to find out a few days ago her aunt was still alive.
"Victoria called her friend on her Russian number and said she was alive," she said.
"She couldn't call in Ukrainian telephone numbers.
"Unfortunately, I have a few colleagues who stayed in Mariupol and we don't know about them, if they are still alive. And my daughter's teacher and doctor are also [missing]."
'If someone has information, write or call me'
Ukrainian human rights group Magnolia has received reports of about 2,000 missing children since the start of the war, including in Mariupol.
Previously the organisation registered about 300 such cases per year, one of its representatives, Marina Lypovetska, told Reuters.
Mr Cherepanov's website is only one of the ways that Mariupol's residents are looking for each other.
People have flooded social media sites with photos and pleas for information about missing loved ones.
The Telegram channel Mariupol Now is sharing information on evacuation efforts and on civilians still in the city.
One recent post read: "Mariupol, Zelinskoho Street 13. Vika Morozova and her children, twin boys Sasha and Sergei. They were in a basement with the people who lived in the house. If someone has information, write or call me."
More than145,000 people have signed up to a group on Facebook called The search for relatives and friends Mariupol 2022, where members share contact details and photos of missing people.
One member shared a post tagged "Survivors, maybe you'll recognise relatives" with photos of people who looked like evacuees, clutching blankets and bags.
"Where are these people? The woman in a black hat with a kitten looks like my friend," replied one user.
'We were ready to go back to Mariupol'
Kiran Ramaiah, who is now in Finland, said not being in contact with his wife's family in Mariupol for a month was "mental trauma and torture".
After contacting all their friends and relatives, he and his wife set up an Instagram group with local shops and a Telegram group of neighbours to search for news.
Mr Ramaiah's in-laws eventually managed to send a text message saying they were alive.
Amid the shelling, they were able to get mobile phone signal by climbing to the ninth floor of their building.
Mr Ramaiah said they had since escaped Mariupol by going to Russia.
“It was a very stressful situation that I cannot even describe," he said.
"We were ready to go back to Mariupol and fight for them."
ABC/Reuters
