Helicone vs. AssemblyAI

Both pass through provider rates at 0% markup. Here’s what AssemblyAI’s LLM Gateway adds for Voice AI:

0% markup on both—plus native speech-to-text Helicone doesn’t offer
Transcribe and reason over audio in one pipeline—Helicone observes text only
Default-on EU data residency, opt-in zero data retention, and a BAA when you need one

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At a glance: Helicone vs. AssemblyAI

Model

AssemblyAI LLM Gateway

Helicone

Pricing

0% markup

Speech-to-text

First-party models—no extra hop

—

Models

25+ curated production models

100+ models

Automatic fallbacks

Configurable per-model

Provider-level

EU data residency

Default-on for EU traffic

Selectable region

Zero data retention

Opt-in, per request

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BAA available

Team tier ($799/mo)

Ongoing development

Actively developed

Maintenance mode

OpenAI SDK compatible

Same 0% markup—plus native speech-to-text

Native speech-to-text

Transcribe with AssemblyAI’s own speech models and apply any LLM to the result in one pipeline. Helicone observes text LLM traffic only—it has no native speech or audio.

0% markup

Like Helicone’s gateway, AssemblyAI passes through provider token rates with no markup—and observability isn’t gated behind a separate paid tier.

Automatic fallbacks

Configure a primary model and any number of backups per request. If a provider errors or rate-limits, the Gateway retries the next model—no code changes.

25+ frontier models

GPT, Claude, Gemini, Qwen, Mistral, and more behind one OpenAI-compatible API. New models are added the day they launch.

OpenAI-compatible

Drop into any OpenAI SDK or HTTP client. Change a base URL and a model string, and the rest of your code keeps working.

EU data residency

Route requests through EU-resident infrastructure, on by default for EU traffic—not just a region you select yourself.

Zero data retention

Opt into zero data retention per request or project-wide, so prompts and responses are never stored.

BAA available

Sign a Business Associate Addendum for applications that process PHI—without gating it behind a premium observability tier.

Start building

Get your free API key and make your first Gateway call in minutes—no commitments or minimums.

Live demo

Pick a model. Take action on your audio.

The same transcript, four different jobs, four different models — all routed through one endpoint.

Prompt

What is runner's knee?

claude-opus-4-7 412 ms · 47 tokens

Based on the transcript, runner's knee is a condition characterized by pain behind or around the kneecap. It is caused by overuse, muscle imbalance and inadequate stretching. Symptoms include pain under or around the kneecap and pain when walking.

Need speech, not just observability?

Get 0%-markup model access with native speech-to-text and default-on data governance in one actively developed, OpenAI-compatible API.

Get your API key

Playground

We’re not playing around—but you can

Put our Voice AI models and the LLM Gateway to the test in our no-code playground.

Explore Playground

Frequently asked questions

: Helicone is an observability-first platform with a 0%-markup AI Gateway, while AssemblyAI’s LLM Gateway pairs 0%-markup model access with native, first-party speech-to-text in one pipeline. Helicone’s strength is deep LLM monitoring; AssemblyAI’s is audio support and default-on data governance. Choose AssemblyAI when you’re building on voice; choose Helicone when your primary need is standalone LLM observability.
: Neither marks up model tokens—both pass through provider rates at 0%. The difference is packaging: with Helicone, advanced observability, HIPAA, and longer retention live in paid tiers ($79 and $799 per month), while AssemblyAI’s Gateway includes no-markup access with governance built in.
: AssemblyAI, because it runs its own speech-to-text models and applies any LLM to the transcript in one pipeline—no second vendor and no extra network hop. Helicone has no native speech or audio; it can log a third-party audio call, but it does not transcribe.
: Helicone was acquired by Mintlify in early 2026, and its standalone product is now in maintenance mode—it receives security updates, new model support, and bug fixes, but active feature development has ended. AssemblyAI’s LLM Gateway is an actively developed, independent product.
: Helicone’s observability—request logging, cost and latency analytics, prompt tracing, evals, and its HQL query language—is genuinely strong and more mature as a dedicated monitoring layer. AssemblyAI’s advantage is elsewhere: native speech, no-markup managed model access, and default-on EU residency and ZDR.
: With AssemblyAI, yes—EU residency is on by default for EU traffic, zero data retention is available per request, and a Business Associate Addendum (BAA) is available for workloads that process PHI. Helicone offers a selectable EU region and HIPAA on its $799/month Team tier, but does not document a per-request zero-data-retention mode.