The world governing body are using two systems, Hawk-Eye and GoalRef, at the Club World Cup in Japan, with one of them to be used at next year's Confederations Cup.
"One of these two systems - we are not going to take both - but one of the two will be used at Confederations Cup and at the 2014 World Cup," Blatter said in Tokyo.
"There were no critical decisions so far," the Swiss added before Sunday's final between Chelsea and Brazil's Corinthians in Yokohama.
"We will make an assessment after the final matches tomorrow. For the time being, we can only say it works."
The British-designed Hawk-Eye, used successfully for many years in cricket and tennis, relies on seven high-speed cameras set up at different angles covering each goal.
GoalRef, a Danish-German project, uses an electronic coil inside the ball and low magnetic waves around the goal.
"The referees are happy to have this help for them because they know now if there is a conflicting situation they will get the accuracy to say if was a goal or not," said Blatter.
"We were speaking of goal-line technology since the beginning of 2000. We had it in the 2007 Club World Cup with the (Cairos) chip in the ball system.
"We saw it didn't work so well so we put the goal-line technology on ice until we had a system that is accurate - and then look what happened.
"In the 2010 World Cup, you remember Lampard scored a wonderful goal (against Germany) which landed at least 70 centimetres behind the line.
"The officials couldn't see it, wouldn't see it - I don't know. But anyway the game continued.
"At that time as president of FIFA, I said if I was still president of FIFA in 2014 then we cannot afford to have the same situation when an accurate system exists."
Both systems being used at the Club World Cup, which relay information to the referee via a vibrating wristwatch in a split second, have passed all pre-game tests with no problems.
The FA and Premier League have backed Hawk-Eye, though UEFA president Michel Platini remains stubbornly opposed to the use of technology.
"We have found two accurate systems in the past year and therefore the goal-line technology has been introduced," said Blatter.
"We will use it for the highlight of the World Cup. We are very confident, the referees are confident and the players are confident that they know if a goal is scored or not."