Flagsmith vs Tessary
Flagsmith and Tessary are both developer tools tools aimed at developers and small businesses. Both have a free plan.
Open-source feature flags and A/B tests, cloud or self-hosted
Open-source monitoring that finds why production AI agents fail
| Pricing | Open source · $45 | Open source |
| Starting price | $45/mo | Not published |
| Free plan | Yes | Yes |
| Free trial | 14 days | — |
| Built for | Developers, Small businesses, Enterprise | Developers, Small businesses, Enterprise |
| Platforms | web | web, linux |
| Country | GB | — |
| Rating | — | — |
Choose Flagsmith if
Engineering teams that want open-source, self-hostable feature flags with optional cloud hosting and built-in experiments.
- Open source under BSD-3-Clause with a real self-hosting path
- Unlimited flags, environments and segments on every plan
- Wide SDK coverage including mobile and Flutter
Look elsewhere if: Teams that want flags bundled with product analytics or a large enterprise vendor ecosystem (PostHog, LaunchDarkly).
Choose Tessary if
Engineering teams running AI agents in production with OpenTelemetry traces who want every trace checked and failures explained.
- Apache 2.0 open source with free self-hosting
- Checks every trace instead of a sampled subset
- RCA links failures to specific commits when a repo is connected
Look elsewhere if: Teams that want a mature, fully supported observability suite or an eval-first workflow (Datadog, Braintrust).
Flagsmith vs Tessary pricing
Flagsmith
- Free$050k requests/mo, 1 team member, 1 project
- Start-Up$45/mo$40/mo billed yearly; 1M requests, 3 members, A/B testing
- Scale-Up$300/mo$250/mo yearly; 5M requests, SAML SSO, roles, audit logs
- EnterpriseCustomPrivate cloud or on-prem, SLA, onboarding, priority support
Tessary
- Open Source$0Self-host with Docker Compose; all core features
- Cloud Free$010k traces/mo, 1 GB, 30-day retention, $10 one-time RCA credit
- PaidCustomCustom classifiers, managed dedicated instance, Slack support
Flagsmith · Key features
- Feature flags and remote config with user, segment and percentage targeting
- Bayesian A/B experiments built directly on existing flags
- Scheduled flags, multivariate flags and change requests
- SDKs for JavaScript, React, iOS, Android, Flutter, Python, Go and Rust
- OpenFeature provider for cloud, private cloud and self-hosted setups
- Audit logs, roles and permissions for governance
Cons
- Free cloud plan allows only one team member
- SSO, roles and audit logs require Scale-Up at $250 or more a month
- Experiments v1 supports one primary metric per test
Tessary · Key features
- Classifiers run on every production trace with no sampling
- Built-in checks for drift, tool errors, secret leaks and malformed output
- LLM triage groups real deviations into trackable cases
- Root-cause analysis over failing traces and your GitHub repository
- OTLP ingestion over HTTP and gRPC with OpenTelemetry gen_ai conventions
- PII redaction before traces are stored
Cons
- Very new project with a short track record
- Paid plan prices are not published
- Frustration classifier requires your own OpenRouter or TypeSafe key
Flagsmith vs Tessary: FAQ
Do Flagsmith and Tessary have a free plan?
Yes, both Flagsmith and Tessary have a free plan; paid plans add more usage and features.