comparison · infra vs platform
Retell vs Synthflow in 2026: Pricing, Features, Latency, Real Tradeoffs
By builders, for builders.
Retell and Synthflow are the two platforms most often compared by AI voice agency operators in 2026, but they are not the same kind of thing. Retell is voice infrastructure: a hosted runtime that wires LLM, TTS, STT, and telephony into one duplex stream, with an API, SDKs, and a developer-friendly dashboard. Synthflow is an agency-focused voice platform with multi-tenant sub-accounts, a basic campaign layer, and white-label features built on top of similar infrastructure. The honest read in 2026: Retell is cheaper per minute and faster on latency, but you have to build agency features yourself. Synthflow gives you agency features out of the box but at a $3,400 per month agency tier and a public strategic pivot toward enterprise BPOs that has left many small-and-mid-sized agencies under-served. The short version: pick Retell if you have devs and want maximum control. Pick Synthflow if you want pre-built multi-tenant and can afford the agency tier. If you are running between 5 and 30 voice clients and neither feels right, look at where Hermes fits.
Side-by-side comparison
| Capability | Retell | Synthflow |
|---|---|---|
| Pricing model | Per-minute bundled or BYO-keys | Monthly tiers + per-minute overage |
| Entry price | Pay-as-you-go from $0.07/min | $29 to $99/mo with included minutes |
| Agency tier price | N/A, no agency tier | $3,400/mo |
| Per-minute all-in cost | $0.07 to $0.31 | ~$0.13 plus tier monthly |
| Built-in CRM | No | Basic contacts and campaigns |
| White-label sub-accounts | No turnkey | Yes on agency tier |
| Multi-tenant client billing | Build it yourself | Included on agency tier |
| Voice models in catalog | Native + BYO ElevenLabs, Cartesia, etc. | Curated catalog + BYO |
| Latency p50 | ~600 to 850 ms | ~800 to 1,100 ms |
| Latency p95 | ~1.2 to 1.6 s | ~1.5 to 2.0 s |
| Integrations | Webhooks + custom functions | Native + Zapier + webhooks |
| Agency-friendly out of box | No, infra layer | Yes on agency tier |
| SOC 2 / HIPAA available | Available on enterprise plans | Available on agency+ tiers |
| Strategic direction 2026 | Infra excellence + dev tools | Pivoting upmarket to enterprise BPO |
Best for: Retell
Pick Retell if your team is dev-friendly and you want raw control over the voice stack with the lowest published latency in the category. Retell's BYO-keys model makes it cheapest at scale for teams who already manage OpenAI and ElevenLabs accounts. The flow-style UI is more opinionated than Vapi and easier to ship a working agent in a day. Where Retell falls short for agencies is the missing multi-tenant layer: you bring your own billing, your own CRM, your own client portal, and your own white-label. See the Retell documentation for current pricing and provider catalog.
Best for: Synthflow
Pick Synthflow if you want agency features (multi-tenant, white-label, sub-accounts, basic campaigns) out of the box without engineering them yourself, and you can afford the $3,400 per month agency tier. Synthflow is the fastest no-code path to a working multi-tenant voice agency for operators who do not want to think about infrastructure. The two caveats in 2026 are price (the $3,400 agency tier is high relative to per-client revenue for sub-15-client agencies) and direction: Synthflow's public positioning has shifted toward enterprise BPOs since their $20M Series A, and several agency operators have reported that small-and-mid-sized agency support has degraded as the company moves upmarket. See the Synthflow website for current pricing.
Where Hermes fits if you outgrew both
Hermes is the operating layer for AI voice agencies. We use Retell-class infrastructure underneath but expose it through one workspace per client, with native CRM, transparent voice overage at $0.24 per minute flat, and white-label demo pages bound to your own CNAME. The pricing slot sits between Retell-alone (cheap-but-DIY) and Synthflow's $3,400 agency tier: Starter at $149 per month for 3 workspaces, Business at $399 for 7, Agency at $699 for 20 with 2,000 included minutes pooled. For a 5-to-30-client agency that is a $1,500 to $2,700 per month savings versus Synthflow at the agency tier, with the multi-tenant features still included.
| Capability | Retell alone | Synthflow agency tier | Hermes Agency |
|---|---|---|---|
| Monthly base | $0 (usage only) | $3,400 | $699 |
| Per-minute overage | $0.07 to $0.31 | ~$0.13 + base | $0.24 flat |
| Multi-tenant workspaces | Build it yourself | Yes | 20 included |
| Native CRM | No | Basic | Native contacts, pipeline, sequences |
| White-label demo pages | Build them yourself | Yes | CNAME-bound, included |
Related: Hermes vs Synthflow direct, Vapi vs Retell, Vapi vs Synthflow.
FAQ
Is Retell cheaper than Synthflow?
On a per-minute basis Retell tends to be cheaper for agencies who can manage their own model keys. Retell runs $0.07 to $0.31 per minute depending on voice tier and BYO-keys discount. Synthflow's pricing has shifted upmarket in 2026: the entry plan starts around $29 to $99 per month with 50 to 300 included minutes and overage at roughly $0.13 per minute, but their agency plan is $3,400 per month for the multi-tenant features. For a single workload Synthflow's entry tier can be cheaper. For 5+ clients on a multi-tenant agency plan, Retell + your own build will land lower than Synthflow's $3,400 agency tier.
Which has lower voice latency, Retell or Synthflow?
Retell tends to publish lower p50 latency, in the 600 to 850 ms range under default configurations with their native voice models. Synthflow benchmarks publish p50 closer to 800 to 1,100 ms depending on the voice and provider mix. Both are within human-conversational tolerance, but on long-tail outbound campaigns Retell tends to feel snappier in side-by-side blind tests with operators. As always your audible latency will be dominated by your network path and provider choice, not the platform brand.
Which is better for building an AI voice agency, Retell or Synthflow?
Synthflow is explicitly built with agency features (multi-tenant, white-label, sub-accounts). Retell is infrastructure that you bolt agency features onto. If you want zero-code multi-tenant out of the box and you can stomach the $3,400 per month Synthflow agency price tag, Synthflow is the faster path. If you have devs and want lower per-client cost, Retell + your own multi-tenant layer (or an aggregator like Hermes) lands cheaper for most agencies under 30 clients. Synthflow has also signaled a strategic pivot toward enterprise BPO since their Series A, which has left many sub-30-client agencies feeling under-served. That is the real tradeoff in 2026.
Does Synthflow include a CRM?
Synthflow includes a basic contact and campaign layer but it is not a full CRM. Most agencies on Synthflow still pair it with GoHighLevel for sequences, pipeline, and lifecycle automation. Retell does not include a CRM at all. If you want voice + native CRM in one platform, that is where Hermes fits: native contacts, pipeline, sequences, and per-workspace ownership without GHL on top.
Does Hermes replace Retell or Synthflow, or work alongside them?
Hermes is the agency operating layer that sits on top of voice infrastructure. We use providers like Retell underneath but expose them through one workspace per client, with native CRM, native multi-tenant billing, and white-label demo pages on your domain. Agencies on Hermes do not need to manage Retell or Synthflow directly. If you have an existing Synthflow agency tier subscription and want to migrate the per-client billing layer to Hermes while keeping your existing agents alive, we have a migration template for that.
Outgrew Retell-alone or paying too much for Synthflow?
Hermes is the agency operating layer. One platform. Your brand. From $149 per month.
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