4 Free & Open Source Alternatives to Gladia (2026)

Gladia offers a speech AI and audio intelligence API, built on its Solaria-1 model, for real-time voice applications. It includes speaker diarization and language detection, supports over 100 languages with code-switching, and offers a recurring free tier. Below are the best free replacements we've tested.

Gladia

Freemium ★ ★ ★ ★ ★ 4.0

Gladia offers a speech AI and audio intelligence API, built on its Solaria-1 model, for real-time voice applications. It includes speaker diarization and language detection, supports over 100 languages with code-switching, and offers a recurring free tier.

Freemium
4 free options
AI Tools
4 / 5
Why people look for alternatives Gladia has a free tier with limitations. Many users seek fully free or open-source alternatives that offer the same capabilities without paywalled features or usage caps.
Gladia software homepage showcasing AI-powered automation tool features 2026 Visit Gladia →

Quick Comparison

Tool Pricing Best for Rating
AssemblyAI
Freemium Building applications requiring advanced audio analysis and LLM integration ★ ★ ★ ★ ★ 4.5
Deepgram
Freemium Developers needing programmatic speech-to-text and real-time streaming ★ ★ ★ ★ ★ 4.5
Rev.ai
Freemium Users needing accurate AI/human transcription, captions, and speech analytics. ★ ★ ★ ★ ★ 4.0
Speechmatics
Freemium Large enterprises and developers building voice AI products ★ ★ ★ ★ ★ 4.5

Detailed Reviews

AssemblyAI

AssemblyAI offers APIs for accurate speech-to-text and advanced audio intelligence, enabling developers to build Voice AI applications with capabilities like summarization, content moderation, and speaker detection.

★ ★ ★ ★ ★ 4.5
Freemium Best for: Building applications requiring advanced audio analysis and LLM integration

Free $50 credit for evaluation; pay-as-you-go starting at $0.15/hr for base transcription, with modular add-ons for audio intelligence features.

3 screenshots — click to enlarge

AssemblyAI Speech Recognition Software Homepage Screenshot 2026 Main interface
AssemblyAI Voice Agent API product screenshot 2026 Settings view

✓ Pros

  • High accuracy (~98.4% WER for Universal-3 Pro)
  • Comprehensive audio intelligence: LeMUR, summarization, content moderation, topic/entity detection, sentiment, PII redaction, speaker diarization.
  • Supports real-time streaming with low latency (~300ms)
  • Supports 99+ languages for async, 6 for streaming
  • Transparent, no-contract pricing
  • Extensive documentation and developer-friendly SDKs
  • Enterprise compliance certifications

✕ Cons

  • Modular, add-on pricing can be complex to calculate total costs
  • Does not offer human transcription
  • Not open-source

Deepgram

Deepgram is an enterprise-grade voice AI platform offering a suite of APIs for speech-to-text, text-to-speech, and audio intelligence applications, trusted by 200,000+ developers.

★ ★ ★ ★ ★ 4.5
Freemium Best for: Developers needing programmatic speech-to-text and real-time streaming

Free $200 credit then pay-as-you-go. Growth plan starts at $4,000/year, Enterprise plan starts at $15,000/year.

3 screenshots — click to enlarge

Deepgram Transcription Dashboard Homepage Screenshot 2026 Main interface
Deepgram Speech-to-Text Software Tool Interface Screenshot 2026 Settings view

✓ Pros

  • High-accuracy transcription
  • Real-time and batch processing
  • Scalability and performance
  • Advanced features like key-term prompting, speaker diarization, smart formatting, redaction
  • Supports text-to-speech, summarization, sentiment analysis, and intent recognition
  • Enterprise-grade trust with SOC 2 Type 1 & Type 2 Certified and HIPAA Compliant
  • Flexible pricing model

✕ Cons

  • Real-time streaming requires dedicated infrastructure, instant processing, and complex WebSocket management
  • No built-in conversational AI (when compared to some alternatives)

Rev.ai

Rev.ai is an API-driven platform offering highly accurate AI and human speech-to-text, captioning, and subtitling for audio and video. It provides flexible deployment and advanced AI insights.

★ ★ ★ ★ ★ 4.0
Freemium Best for: Users needing accurate AI/human transcription, captions, and speech analytics.

Permanent free plan with 45 minutes of AI transcription/captions monthly; new users get five free hours of API usage.

2 screenshots — click to enlarge

Rev.ai Transcription Software Homepage Screenshot 2026 Main interface
Rev.ai Pricing Plans for transcription services 2026 Settings view

✓ Pros

  • Offers both highly accurate AI and human transcription services.
  • Supports 58+ languages for asynchronous and 9 languages for streaming transcription.
  • Provides various AI insights including Language Identification, Topic Extraction, and Sentiment Analysis.
  • Offers flexible deployment options (cloud or on-premise).
  • High reliability with 99.99% uptime and robust data security (SOC 2 Type II, HIPAA compliant).
  • Easy API integration with SDKs and comprehensive documentation.
  • Includes a permanent free plan with 45 minutes of AI transcription/captions per month.
  • New users receive five free hours of API usage credit.
  • Does not train external LLMs on user data, ensuring privacy.
  • Provides open-source ASR and diarization models, and SDKs.

✕ Cons

  • Pricing structure can be complex.
  • Real-time streaming is not a primary focus, primarily batch processing.
  • Some AI speech understanding features may be basic compared to competitors.
  • Some AI tiers might be less accurate than alternative free tools.
  • Lacks integrated collaboration features like shared workspaces.

Speechmatics

Speechmatics is a leading Voice AI company providing accurate, real-time, multilingual speech-to-text and text-to-speech APIs, trusted by enterprises for various use cases including live captioning, voice assistants, and medical transcription.

★ ★ ★ ★ ★ 4.5
Freemium Best for: Large enterprises and developers building voice AI products

Free tier offers 480 minutes/month for Speech-to-Text and 1 million characters/month for Text-to-Speech. Paid plans start from $0.24/hour.

3 screenshots — click to enlarge

Speechmatics Speech Recognition Software Online Platform Homepage Screenshot 2026 Main interface
Speechmatics Pricing Plans Overview 2026 Settings view

✓ Pros

  • Market-leading accuracy across many languages and accents.
  • Real-time and batch transcription.
  • Flexible deployment options (cloud, on-prem, on-device).
  • Enterprise-grade security and compliance (ISO 27001, SOC2 Type II, GDPR).
  • Speaker diarization included as a core feature.
  • Comprehensive language coverage (55+ languages).
  • Strong developer support with APIs and SDKs.
  • Customization options for vocabulary and models.

✕ Cons

  • Primarily designed for large-scale enterprise needs, less ideal for personal/small business users.
  • Not an "out-of-the-box" solution; setup can be complex depending on use case.

Some links are affiliate. We never accept payment for inclusion or ranking.