Retell vs Synthflow: Who wins in 2025?

Retell - a quick overview

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Retell AI was founded in 2023 by Todd Li, Evie Wang, Bing Wu, Weijia Yu, and Zexia Zhang. Based in Saratoga, California, the company specializes in creating AI-powered voice agents for businesses. These agents are designed to handle customer calls efficiently by integrating large language models (LLMs) with speech capabilities. Retell AI's solutions cater to mid-market to enterprise customers looking to enhance their customer service operations.

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Retell AI's core function is providing a platform that allows developers to build human-like conversational experiences with features like interruption handling and low-latency interactions. This makes it ideal for businesses dealing with high call volumes.

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In the following section, we'll explore Retell AI's features compared to Synthflow and other similar platforms. This comparison will cover key aspects such as pros and cons, pricing models, user reviews, and how each platform meets different business needs.

Retell's Features

• 1. Dynamic Knowledge Base Integration Retell AI offers a robust knowledge base feature that integrates webpages, documents, and custom content to keep its AI agents informed and efficient. This ensures real-time updates for accurate responses without manual intervention. While similar to Ringly.io's knowledge base, Retell lacks the extensive e-commerce-specific integrations like Shopify or WooCommerce offered by Ringly.io.
• 2. Real-Time Voice Interactions Retell provides natural voice interactions with low latency for seamless customer communication. However, it does not match Ringly.io’s ability to personalize voices or add background noise for a more human-like experience.
• 3. Agent Customization and Multilingual Support With support for multiple LLMs and languages, Retell allows businesses to tailor their AI agents extensively. While this is comparable to Synthflow’s multilingual capabilities, it falls short of Ringly.io’s 19-language support combined with personalized conversational tones tailored specifically for e-commerce needs.
• 4. Post-Call Analytics and Monitoring Tools Retell includes post-call analytics that track call outcomes and provide insights into agent performance through dashboards. Although useful, these features are less comprehensive than Ringly.io’s advanced call analysis tools that include sentiment detection and actionable improvement suggestions during calls.
• 5. Scalability with Enterprise-Level Reliability Designed for large-scale operations, Retell ensures high uptime reliability suitable for enterprise clients needing robust infrastructure support. However, it does not offer the same level of automation in abandoned cart recovery or order status checking as seen in Ringly.io's solutions tailored specifically toward scaling e-commerce businesses efficiently.

While Retell excels in flexibility across industries with its scalable platform and multilingual capabilities, it lacks the targeted features like abandoned cart recovery or deep integration options that make Ringly.io superior in addressing specific business pain points within e-commerce environments.

Pros

• Ease of Use - Users frequently praised Retell's intuitive interface, making it easy to build, integrate, and manage voice AI solutions without much technical complexity.
• Responsive Customer Support - Many reviewers highlighted the highly responsive support team that quickly addresses issues or implements requested features.
• Cost Efficiency - Unlike competitors with platform fees, Retell only charges for API usage. This makes it a cost-effective solution for businesses looking to scale without incurring unnecessary expenses.
• High Customization Capabilities - The platform allows users to create stateful multi-prompt agents tailored to specific needs while integrating seamlessly with large language models like OpenAI.
• Quick Deployment - Businesses appreciated how quickly they could deploy voice AI agents using Retell’s tools, significantly reducing time-to-market for their projects.

Cons

• Limited Scalability in Agent Deployment - Some users noted restrictions on the number of agents that can be deployed simultaneously as a drawback when scaling operations.
• Occasional Latency Issues - A few reviewers mentioned experiencing latency problems during high-demand scenarios which could impact real-time interactions negatively.
• Lack of Advanced Customization Options for Voices - While functional overall, some users expressed a desire for more diverse customization options in voice settings (e.g., male voices).
• Unreliable Vendor Perception by Some Users - A minority of reviewers felt that switching costs were the only reason they stayed with Retell due to concerns about reliability as a vendor.
• Feature Development Pace May Be Overwhelming – Although frequent updates are generally positive, some found the rapid pace challenging as it required constant adaptation to new features or changes in functionality.

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Synthflow - a quick overview

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Synthflow AI was founded in 2023 in Berlin by Hakob Astabatsyan, Albert Astabatsyan, and Sassun Mirzakhan-Saky. This innovative startup offers a no-code platform that empowers businesses to create and deploy AI voice assistants easily, automating customer interactions and enhancing customer experiences. Synthflow serves over 1,000 customers globally, targeting small and medium-sized enterprises looking to streamline their communication processes.

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Synthflow's key features include real-time appointment scheduling, customer support, and seamless integration with various tools like CRM platforms. The platform is designed to be user-friendly, allowing businesses to deploy voice assistants without needing technical expertise.

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In the following section, we’ll explore Synthflow AI's features, pros and cons, pricing, and user reviews, comparing them with other voice AI solutions like Retell and Ringly.io. This comparison will help you understand where Synthflow stands and whether it's the right choice for your business needs.

Synthflow's Features

• AI-Powered Call Handling
  Synthflow provides AI agents capable of handling inbound and outbound calls with natural, human-like interactions. These agents can answer customer inquiries, route calls to the right department, and even manage appointment bookings. While similar to Retell’s conversational capabilities, Synthflow lacks Ringly.io’s advanced e-commerce-specific features like abandoned cart recovery.
• Multi-Language Support
  With support for over 20 languages, Synthflow ensures global accessibility for businesses catering to diverse audiences. This is comparable to Ringly.io but slightly behind in language breadth compared to Retell's more extensive customization options.
• Customizable Voice Agents
  Businesses can personalize their AI agent's voice and tone to align with their brand identity. This feature mirrors both Retell’s flexibility in voice customization and Ringly.io’s ability to add background noise or adjust tones for specific use cases.
• CRM Integration
  Synthflow integrates seamlessly with popular CRMs like Salesforce and HubSpot, enabling efficient data synchronization during or after calls. While this matches Ringly.io's integration capabilities (over 7,000 tools), it falls short of the real-time action triggers offered by Ringly.io during live calls.
• Call Analytics Dashboard
  The platform offers detailed analytics on call performance metrics such as resolution rates and customer satisfaction scores (CSAT). Although useful for improving service quality, it lacks the depth of insights provided by Ringly.io’s mood analysis or actionable suggestions based on call trends.
• Appointment Scheduling Automation
  Like Retell AI and Ringly.io, Synthflow supports automated appointment booking integrated with calendar apps. However, its scheduling functionality does not extend beyond basic setups seen in competitors like Retell or the personalized booking experiences offered by Ringly.io.

Synthflow delivers solid foundational features but lacks some advanced functionalities that make competitors stand out—such as real-time order tracking (Ringly) or ultra-low latency conversational models (Retell).

Pros

• Ease of Use - Users frequently praised Retell's intuitive interface, making it easy to build, integrate, and manage voice AI solutions without much technical complexity.
• Responsive Customer Support - Many reviewers highlighted the highly responsive support team that quickly addresses issues or implements requested features.
• Cost Efficiency - Unlike competitors with platform fees, Retell only charges for API usage. This makes it a cost-effective solution for businesses looking to scale without incurring unnecessary expenses.
• High Customization Capabilities - The platform allows users to create stateful multi-prompt agents tailored to specific needs while integrating seamlessly with large language models like OpenAI.
• Quick Deployment - Businesses appreciated how quickly they could deploy voice AI agents using Retell’s tools, significantly reducing time-to-market for their projects.

Cons

• Limited Scalability in Agent Deployment - Some users noted restrictions on the number of agents that can be deployed simultaneously as a drawback when scaling operations.
• Occasional Latency Issues - A few reviewers mentioned experiencing latency problems during high-demand scenarios which could impact real-time interactions negatively.
• Lack of Advanced Customization Options for Voices - While functional overall, some users expressed a desire for more diverse customization options in voice settings (e.g., male voices).
• Unreliable Vendor Perception by Some Users - A minority of reviewers felt that switching costs were the only reason they stayed with Retell due to concerns about reliability as a vendor.
• Feature Development Pace May Be Overwhelming – Although frequent updates are generally positive, some found the rapid pace challenging as it required constant adaptation to new features or changes in functionality.

Pricing - Retell vs Synthflow

Note: The pricing information below is accurate at the time of writing and may be subject to change. For the most up-to-date pricing, please visit each company's pricing page.

Retell pricing

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Synthflow pricing

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Ringly.io pricing

Ringly.io delivers the perfect balance of affordability and features. Unlike competitors who force you into expensive tiers, Ringly.io includes all core features even in its free plan. The simple, transparent pricing scales based on your actual usage, with no surprise fees.

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Online customer reviews: Retell vs Synthflow

Retell AI

Retell AI is praised for its ease of use, customer support, and integration capabilities. It specializes in creating human-like voice agents with features like multilingual support and compliance with standards such as SOC 2 and HIPAA. Retell AI has a 5.0-star rating based on user feedback.

What users are saying about Retell:

"Exceeds expectations" - Anonymous User, Healthcare Manager. Retell's ability to create natural conversational experiences has been transformative for our patient management system...

"Limited customization options" - Anonymous User, Sales Manager. While the platform excels at handling delicate conversations, the lack of a visual flow builder makes it challenging for sales teams to collaborate effectively...

Synthflow AI

Synthflow AI is known for its intuitive interface, scalability, and robust feature set that includes multilingual support and extensive integrations. It offers tiered pricing plans suitable for businesses of all sizes. Synthflow has a 4.4-star rating from 353 reviews on G2, reflecting generally positive user experiences.

What users are saying about Synthflow:

"Super easy to use!" - Michael Wimmer, Director at AI Launch. I built an AI receptionist in less than seven minutes! The platform’s clone feature is amazing—it even made my agent sound just like me...

"Overwhelming setup process" - Anonymous User, Small Business Owner. The initial configuration was not straightforward; better onboarding or documentation would make it easier for new users...

What users are saying about Ringly.io:

Ringly.io is known for its simplicity, and a focus on e-commerce, with features like abandoned cart recovery and order status lookups. It has a 4.8 star rating from 12 reviews on Product Hunt and other platforms.

"it stands out significantly ahead" - Bertrand, Director. We are at the initial stage of testing and have made only a few calls so far. Consequently, I have rated the product with four stars for now. However, I must express that the product has shown significant promise. When compared to competitors, it stands out significantly ahead.

"This is such a great product" - Jim Miranda, Founder. This is such a great product. I have been with you for less than a week and already closed 3 deals with it."

"It really sounds like a human" - Laix, Founder. Tried Ringly.io today and the quality of the phone calls surprises me! It really sounds like a human, and it reacts really fast. Will need to deploy it in action to see the full capabilities.

"How to automate customer service? -> Ringly.io" - Sidra Husnain, Founder.

Retell vs Synthflow: Which is best for you?

Who Retell is best for…

• Mid-sized to large businesses that need AI voice agents to handle lots of calls quickly and efficiently.
• Tech-savvy teams who want deep customization and are comfortable working with APIs and developer tools.
• Enterprises that prioritize reliability and want a scalable solution with multilingual support and analytics.
• Companies in healthcare, finance, or customer service looking for HIPAA- or SOC 2-compliant AI phone solutions.

Who Synthflow is best for…

• Small to mid-sized businesses looking for an easy way to set up AI phone agents without any code.
• Teams with limited tech experience who want a simple drag-and-drop builder and quick launch time.
• Businesses focused on booking calls, setting appointments, or connecting to CRMs like HubSpot or Salesforce fast.
• Agencies or resellers looking to white-label and offer AI voice tools under their own brand.

Who Ringly.io is best for…

• E-commerce stores of any size that need smart phone agents to recover carts, check order statuses, and recommend products.
• Founders and teams who want to save time and close more sales without talking to every customer manually.
• Businesses that want all features without upselling – even the free plan includes core features, making it budget-friendly.
• Anyone wanting the most human-like voice AI with personalized tones, background noise, and instant responses.

Our take: While Retell and Synthflow each have strong points, Ringly.io stands out as the best all-in-one option for most businesses – especially in e-commerce. It balances amazing voice quality, advanced features, easy-to-use tools, and fair pricing. Whether you're just starting out or scaling fast, Ringly.io gives you everything you need without locking essential features behind high-price plans.

Why Ringly.io is a Better Choice

Highly Rated: 4.8/5

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Founded in 2024 in Rotterdam, the Netherlands, by Maurizio Isendoorn and Ruben Boonzaaijer, Ringly.io is revolutionizing e-commerce customer service with AI phone agents.Designed for online businesses, Ringly handles customer calls on autopilot—solving support issues, recovering abandoned carts, and even boosting sales—at just 20% of the cost of human agents.‍

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With 1,300+ customers, Ringly.io is the go-to solution for e-commerce stores looking to scale without scaling their support team. With award-winning technology (BubbleCon 2024's "Most Innovative App"), Ringly.io transforms your phone system into a revenue-driving powerhouse—without the headaches of traditional call centers.‍

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Features that make Ringly.io the #1 alternative to Retell and Synthflow:

No-code setup, instant results – Ringly.io is ready to go in minutes. Just add your website, docs, or text—no engineering required—and your AI phone agent instantly understands your business. It even updates automatically as your website changes.‍‍‍

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AI-powered sales & support – Ringly.io does both inbound and outbound calls. Recover 35%+ of abandoned carts with automated follow-up calls, provide real-time order tracking from Shopify, and convert more customers with personalized AI-driven conversations—not just reactive support.‍‍

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Advanced analytics for smarter decisions – Ringly.io gives you real-time call data, customer intent tracking, and performance reports—helping you optimize support and sales strategies.‍‍‍

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Scalable pricing without enterprise contracts – Ringly.io offers transparent, scalable pricing—pay for what you use, no locked-in contracts.‍

Final Thoughts

Choosing the right AI phone agent platform depends on your business goals, technical resources, and growth stage. While Retell and Synthflow both offer impressive solutions, Ringly.io stands out for its unique approach—giving you powerful features and real business results right out of the box.

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Whether you're focused on efficiency, ease of use, or e-commerce performance, here's a quick breakdown to guide your choice:

• Retell AI: Best for mid- to large-sized businesses with technical teams looking for a high-performance platform that integrates with custom systems. Ideal if you want full control over API-level customization and multilingual scalability.
• Synthflow: A great pick for small to medium-sized teams that want a no-code, plug-and-play experience. Perfect for quick setups, appointment scheduling, and CRM-related use cases—especially if your team isn’t super technical.
• Ringly.io: The optimal all-in-one solution—especially for e-commerce. It handles support, recovers abandoned carts, and boosts conversions automatically, all without the need for coding or complicated setup. It's fast, easy, and cost-effective, with all the features available from day one—even on the free plan.

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So while Retell wins on customization and Synthflow shines in simplicity, Ringly.io quietly combines both—with human-like voice AI, e-commerce smarts, and transparent pricing that lets you grow without surprises.

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In short: if you're looking for AI phone agents that aren’t just smart, but actually drive sales and support on autopilot—Ringly.io is your best bet.

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Want to compare other players in the market> Check out our other comparisons:

• Synthflow vs Bland
• Retell vs Bland