Postgres 10

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CREATE TABLE services (id serial, properties text);

insert into services (properties) values 
('{"url": "www.example.com"}');
select * from services;

CREATE TABLE

INSERT 0 1

id
properties

1
{"url": "www.example.com"}

SELECT 1

update services
set properties = replace(properties,'example','domain')::jsonb
where properties::json->>'url' = 'www.example.com';

UPDATE 1

select * from services;

id
properties

1
{"url": "www.domain.com"}

SELECT 1