An emerging instant messaging tool called Bullet Messaging has received 150 million yuan ($21.96 million) in funding after its first week of operation, gaining traction among internet-savvy Chinese users and posing an imminent threat to social media veteran WeChat.

Developed by Kuairu Technology, which is invested by Beijing-based smartphone maker Smartisan Technology, Bullet Messaging has quickly become the most-downloaded free offering on Apple's App Store in China, according to data from app analytics firm App Annie.

The financing was confirmed on Wednesday via a microblog posted by Smartisan's charismatic founder Luo Yonghao, who is known for staging entertaining product launches that people pay to attend. Investors are flocking in, he said.

The app offers several features that are missing from WeChat, the most significant of which is a real-time speech-to-text transcription ability that has helped fuel its meteoric rise.

The app automatically generates transcriptions of spoken messages, and an audio clip is attached to each message that allows users to listen and check for accuracy. It also supports message replays by dragging the voice bar to a designated position.

In comparison, voice messages sent via WeChat can only be translated into typed messages manually, and going through each and every message can be daunting as users might accidentally play the voice message out loud.

Chinese voice-recognition specialist iFlytek Co Ltd is among numerous artificial intelligence companies backing the technology behind the feature. Kuairu claimed the transcription feature is accurate 97 percent of the time in Mandarin.

The app also introduces a newsfeed function and tailored feeds based on people's interests and habits powered by algorithms. However, some users have reported it contains vulgar content that would not be allowed on WeChat.

These features have aroused consumer interest, which is a long sought-after goal for Smartisan, said Wan Yi, an internet analyst from consultancy Analysys.

"From the investors' point of view, it's been quite a while since a blockbuster messaging app has surfaced since WeChat and created such a buzz on social media... It has certainly piqued their interest," he said.

Skeptics, however, think its popularity will be fleeting. Hong Bo, an independent IT commentator, said the oversimplified functions of Bullet Messaging and the fact an entire internet ecosystem that has largely been built around WeChat would make it too costly for people migrate to a new platform and get hooked for long.

"WeChat's dominance is unshakable given it is the super app designed for the mobile internet age. A genuine rival would emerge only when the entire internet ecosystem had entered a new phase," he said.

Luo, founder of Smartisan, said it would be unrealistic to uninstall WeChat.

Once the hype has died down, the app could target users who prioritize effective and efficient communications, according to Wan.

"The app is unlikely to uproot WeChat," Wan said. "But it's good enough to take a slice of the pie."