Launched in 2023, Synthflow AI is quickly becoming a recognizable name in the phone AI landscape, with no-code setup, natural-sounding voice agents, and integrations with your favorite tech stack–all seem like a dream come true.
Unless you start with production. Setting up a voice agent in Synthflow AI feels straightforward, but getting it to work flawlessly is another story. Lack of access to buildable tools, no tech support, and limited customisation make users switch to alternatives.
With instant responses in conversations and a low-code infrastructure that provides developer-level control without the complexity, Retell AI is a first choice for Synthflow alternatives.
In this Synthflow AI review, we'll walk you through its features–covering the setup, pricing, and overall performance - and why so many businesses switch from Synthflow to Retell AI.
Synthflow AI is a no-code, drag-and-drop AI voice agent builder that claims to set up a voice agent in minutes, with no technical knowledge or coding required.
The platform is powered by leading LLMs like OpenAI's GPT-4o, that gives your voice bots a human feel with contextual awareness, customizable voices, and tone modulation.
Instead of writing complex code, you use a visual interface and simple text prompts to instruct the AI on its goals, personality, and conversational logic.
Some of its features include:
With Synthflow AI, you get telephone via SIP trunking, multilingual support, and custom workflows, all baked into one unified platform. These AI assistants can handle inbound and outbound calls, book appointments, detect voicemails, and route calls.
Synthflow follows a BELL framework that connects every stage of the voice AI lifecycle into a single operating system, enabling success to be repeated.
Learn track results through real-time analytics and Auto-QA, continuously optimizing your agent's performance.
The BELL framework is an operating model that's built directly into Synthflow AI. It claims that every business using Synthflow experiences BELL in action.
In an ideal world, this would mean smooth responses, low latency, and high conversion for businesses. When tested, the cracks showed immediately, the moment someone went off-script ("wait, can you repeat that?" or "what's the time again?"), the Synthflow voice agent quickly lost track and defaulted back into the same canned line. Felt more like a fancy IVR than an agent.
The platform supports conditional logic, basic memory, and external API calls, but these features remain lightweight compared to low-code tools like Retell AI. You get simplicity and quick setup, but you sacrifice deeper control over prompts, system behavior, and fine-tuned model parameters.
Synthflow AI offers a range of unique features that help small businesses, agencies, and startups launch voice agents for inbound and outbound calls in just a few hours. Let's look at some of them:
This is where Synthflow AI shines. Instead of coding, you build voice agents through a drag-and-drop interface. You can configure, prompt agents, add actions, deploy, and test them in real-time, without having to write a piece of code.
For instance, you can select your voice and control its speed, volume, and latency right from your dashboard.
Synthflow AI allows conditional logic (if the user says X, then do Y), which makes conversations feel dynamic rather than scripted. This visual approach makes complex flow design accessible.
Although the no-code builder is simple, some users find it rigid while setting up advanced branching or passing dynamic variables. If you lack programming knowledge and don't have many complex tasks or customisation requirements, Synthflow's no-code builder can be your way to go.
Synthflow has an average latency of 400ms, which represents the current benchmark for production voice AI agents. The platform achieves this through aggressive optimisation across the entire voice processing pipeline, from audio capture to response generation.
The platform prioritises speed over extensive feature sets, making it ideal for use cases where response time is the primary concern and complex integration isn't required. Eventually, many users complain about similar speed-focused platforms compromising on voice quality, platform stability, and expensive add-on features.
Quick response should be a top differentiator while choosing a voice agent platform, but it shouldn't outweigh customization and feature depth.
An AI agent is only as powerful as the systems it connects to.
Synthflow AI integrates with a range of platforms to help you manage customer conversations, automate workflows, and enhance your agents' capabilities. Some of the integrations include:
Synthflow AI takes multichannel deployment to another level with WhatsApp integration (in addition to phone, web, and chat). Simply connect your voice agent to your WhatsApp Business account and manage calls and texts 24/7 for your customers.
Building an AI voice agent from scratch is expensive. Hiring people and spending months in development while your sales roadmap keeps slipping away further is a costly investment.
Synthflow solves this by providing white label solutions for building voice agents. So, instead of starting from scratch, you plug a ready-made solution and focus on delivering value to clients.
The agency dashboard lets you fully control client subaccounts, enable or disable specific features, and set your own pricing with built-in Stripe rebilling. Your voice agents can easily make outbound calls, answer inbound calls, and schedule appointments 24/7.
However, many agencies have pointed out that, it has:
Retell AI, on the other hand, is optimized for longer, more structured conversations with deeper customization and enterprise-grade compliance. Agencies get more control over LLMs, voices, and client accounts, making Retell better suited for high-volume, production-grade voice AI businesses than Synthflow.
Synthflow AI uses a subscription-based pricing model with four tiers: Pro, Growth, Agency, and Enterprise. Each tier includes concurrent calls, bundled minutes, and workflow limits, with overcharges per minute applied when business exceeds the minutes allotted in their pricing tier.
Even though this might look like a transparent pricing model, businesses scaling past included minutes find it expensive. It becomes challenging to continually switch plans based on your business needs, whereas voice agent solutions like Retell AI charge by the minute.
Plus, the starting plans lack access to the tools required to actually build a usable flow. Many users believe that unless you take the enterprise plan, the platform lacks stability and support from the Synthflow team.
Retell AI offers a pay-as-you-go model with flat rates of $0.07+/minute for AI voice agents and $0.002+/msg for AI chat agents.
One of the downright reviews of Synthflow highlights inaccessible features in the basic plans. Unless you opt for the enterprise plan, the platform is glitchy, and there are only a few tools actually to build a usable workflow.
On the other hand, Retell AI is praised for its affordability, ease of use, customer support, and integration capabilities.
Unlike Sythflow AI, there's no extra cost for key features:
This allows businesses to customize features without any unexpected costs.
Our pricing plan also includes a dedicated voice agent cost calculator, which lets you check pricing based on the number of calls, LLM, voice engine, and telephony used.
New users can explore the platform with 60 minutes of complimentary access and handle up to 20 concurrent calls. Calculate your voice agent pricing from here.
The biggest advantage of Sythflow AI is its no-code platform with a drag-and-drop interface that makes launching voice agents quick and easy. You can define different actions to happen before, during, or after a call.
For example, you can set up an action to pull customer data from your CRM before a call starts or to send a follow-up message when the call ends.
Its flow designer lets you build structured, multi-step AI-voice agents using a visual, node-based interface. Instead of relying on a single prompt, you design conversational pathways where each node handles a specific task—whether that's collecting information, making decisions, or executing actions.
Synthflow's integration with Elevenlabs provides access to incredibly natural-sounding voices in over 30 languages. You can also clone your voice easily by simply uploading some samples.
Besides, even with all the technical pieces in place, Synthflow fails to deliver consistent performance. Users feel the platform is glitchy, which eats up their minutes, and any call with the support team is a nightmare. You will constantly face voice bots that don't work, API issues, or hallucinating bots.
The platform also struggles with complex tasks and deep customisation, leading them to use third-party solutions, which weakens the "all-in-one" promise.
Even supportive reviews admit that latency spikes, awkward phrasing, and difficulty handling barge-ins or ambiguous requests are common pain points mentioned on G2. Synthflow's agents often rely solely on their LLM memory, which can fail in complex, multi-turn dialogues.
If you anticipate needing to scale or require hiring performance without dealing with complex coding, then Retell AI is the way to go.
Retell AI offers superior scalability because it can handle complex functionalities, large user bases, and the integration of advanced technologies. No-code platforms like Sythflow often struggle with scalability as they rely on fixed architectures and predefined limits.
You can also access high-level customisation for your voice agents. Synthflow users often complain about a lack of customisation and independence from third-party tools for the complete setup of their voice agents.
With sub-second response times, transparent pay-as-you-go pricing, and built-in CRM integrations, Retell lets you deploy and scale voice agents quickly, without complex infrastructure setup or lengthy onboarding.
Synthflow AI covers most compliance needs for SMBs, agencies, and even healthcare/finance within its enterprise plan, including:
Synthflow's data-handling protocols maintain strict separation between personally identifiable information (PII) and conversation content, with selective redaction capabilities for sensitive data such as social security numbers, credit card numbers, and protected health information.
Synthflow AI offers support via a ticketing system and private Slack (only for the first 30 days of onboarding), but it tremendously fails to provide it. Users across the internet have reported bad experiences with Synthflow customer support, even on the enterprise plan.
Delays in answering tickets, and support staff lack the technical knowledge to help businesses solve their queries.
Retell AI offers HIPAA, SOC 2 Type 1 and Type 2, and GDPR coverage by default rather than reserving them for enterprise tiers. Its enterprise-grade infrastructure guarantees 99.99% uptime, delivers consistent call quality, minimal latency, and uninterrupted performance at any scale.
Retell AI also provides live onboarding support with chat assistance and fast customer service to help teams launch smoothly. Compared to Sythflow AI, where users are frustrated by poor customer support, Retell AI users are evidence of how our team has helped them overcome technical hurdles.
Based on real user experience, here are a few things Synthflow AI performs well and those that still need improvement.
While Synthflow AI comes as a quick voice agent builder with a no-code, drag-and-drop interface, Retell AI offers lower per-minute rates, more flexible plans, and advanced capabilities, making it an excellent choice for scaling businesses.
Retell AI brings everything Synthflow AI falls short on. Here are some of its features:
Retell also supports international calling in 14 countries, offering global reach at predictable costs.
Better support: Most businesses that switch from Synthflow AI face non-existent support. They are asked to spend more money to get a technical call. With a rating of 4.8/5 (781 reviews), Retell provides quick support via Discord and email.
Retell AI consistently proves to be the smarter alternative, offering flexible plans, advanced compliance, higher reliability, and built-in innovations that Synthflow simply doesn't match.
Choosing between no-code (Synthflow AI) and low-code platforms (Retell AI) for AI voice solutions depends on your business's unique needs, resources, and project goals.
Synthflow AI offers speed, accessibility, and subscription-based Pricing, making it ideal for simple to moderately complex projects with limited coding expertise. On the other hand, Retell AI offers complete control, scalability, and flexibility, making it suitable for complex, large-scale applications that require bespoke solutions.
Build your first real-time voice assistant with Retell AI today and launch in minutes. Talk to our sales team now!
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