HeartMuLa

HeartMuLa is an open source AI music generator built on a 3-billion-parameter hierarchical Transformer model. It takes text prompts or user-supplied lyrics and produces complete songs — vocals, instrumentation, and mastering — in a single generation pass. The model is released under Apache 2.0, meaning it can be downloaded, modified, and used in commercial products without subscription fees or royalty obligations.

What It Does

At its core, HeartMuLa converts natural language descriptions into audio. You describe a mood, genre, and style in plain text, optionally attach lyrics formatted with structure tags like [Verse], [Chorus], and [Bridge], and the model generates a finished track. Songs can run up to six minutes, which is longer than most comparable hosted services allow.

The extended duration is made possible by HeartCodec, a proprietary ultra-low frame rate codec operating at 12.5Hz. This compression approach lets the model maintain coherent song structure across full-length compositions rather than producing short loops or fragments.

A style tag system gives users finer control over the output. Tags span a wide range — ambient, cinematic, lo-fi hip hop, orchestral, metal, reggae, and many more — and can be combined to blend genres or dial in a specific sound.

Who It Is For

HeartMuLa targets two fairly distinct groups.

The first is developers and researchers who want a self-hostable music AI they can inspect, modify, and integrate into their own pipelines. The Apache 2.0 license and Hugging Face distribution make this straightforward, provided the hardware requirements are met (roughly 24GB of GPU VRAM — an RTX 3090 or better).

The second group is content creators, indie game developers, marketers, and musicians who need original, royalty-free audio without ongoing licensing costs. For a YouTube creator who publishes frequently, or an agency producing branded video content, the ability to generate unique background music on demand — and use it commercially — removes a recurring friction point.

Musicians and hobbyists who already have lyrics but lack production resources are also a natural fit. HeartMuLa does not write lyrics autonomously, but it is well-suited to turning existing lyrics into a produced track.

Typical Workflows

The hosted web interface is the fastest entry point. Users describe their music, select style tags, choose a quality tier, and generate. The result is downloadable audio that can go directly into a video, game, or podcast.

For users who need volume, privacy, or deeper customization, local deployment is the alternative. The model weights are available on Hugging Face, and the project provides installation documentation. Cloud GPU services like RunPod or Vast.ai are a practical middle ground for users who want local-style control without owning the hardware.

Lyric-driven workflows follow a similar pattern but require more preparation. Users write their own lyrics, apply the structure tags HeartMuLa recognizes, and submit them alongside a style prompt. The model generates vocals that follow the provided text rather than improvising its own.

Pricing and Access

The hosted service is freemium. New accounts receive a credit allocation on signup, which is enough to evaluate the output quality across a few generations. Beyond the free tier, credits are purchased in packages. There is no mandatory subscription, though subscription plans are available for regular users.

Self-hosting is free in the sense that there are no per-generation fees once the model is running locally. The cost is hardware — either owning a compatible GPU or renting cloud compute.

The Apache 2.0 license covers both the model weights and, by extension, the music generated from them. There are no clauses restricting commercial use or requiring attribution in the output.

Context Among Alternatives

HeartMuLa is frequently positioned against Suno and Udio, the two dominant hosted AI music services. The meaningful differences are structural rather than purely qualitative: Suno and Udio are closed-source, subscription-based, and cloud-only. HeartMuLa trades the polish of a fully managed product for openness, local deployment, and commercial freedom.

For users whose primary concern is output quality and convenience, the hosted services may still be preferable. For users who need control over where their data goes, want to avoid recurring fees, or are building something on top of the model, HeartMuLa is currently the most capable open source option in this category.