10 best feature flag services in 2026: an honest comparison

Strip away the dashboards and a feature flag is an if statement with a subscription fee. The market for hosted if statements is now one of the most crowded in developer tools, and almost every comparison page in it was written by a vendor about its competitors - this one included. Most of them are aimed at enterprises weighing a LaunchDarkly migration. This one is aimed at the rest of us: small teams, indie developers, and early-stage startups who mostly want to know what’s actually free, what the first invoice looks like, and which product fits how they work.

Full disclosure: I build one of the services on this list: Smpl Flags. I’ve put it where I think it belongs and said where I think the others are stronger. This is one of our honest comparisons; the rest live under the comparison tag.

The two kinds of “feature flag service”

Flag-first platforms

ConfigCat, DevCycle, Flagsmith, LaunchDarkly, Smpl Flags, and Unleash sell the flag itself: targeting, environments, kill switches, change history, and the surrounding governance. Some offer experimentation too, but it isn’t why you buy them. Several of these vendors sell remote config too; that side of the market gets its own comparison.

Experimentation platforms (flags included)

GrowthBook, Harness FME, PostHog, and Statsig sell measurement. Flags exist to randomize who sees what, and the statistics engine that tells you what happened next is the actual product. If you adopt one of these, you’re adopting the analytics stack that comes with it - and some of them barely charge for the flags at all.

Pricing models

Every service here charges differently, and how it charges matters more than the sticker price. A meter lands on one of two kinds of numbers: things you can count and control, or things you can only estimate and that grow with success.

Things you can count and control

• Number of flags
• Number of environments

Things you can only estimate and that grow with success

• Number of active users
• Number of connections
• Number of console users
• Number of evaluations
• Number of requests
• Number of servers

Meter on the first kind, and you can compute next year’s bill today. Meter on the second, and the advertised price is just the entry fee: the bill is that number times a growth curve nobody can show you. One wrinkle for the request-metered vendors: SDKs that evaluate flags locally barely move the meter, while SDKs that call home on every check (the default in some vendors’ server SDKs, and the norm for browser and mobile clients) turn every check into a billable request. Same application, very different invoice. Nine of these ten vendors meter something that grows.

Service	The meter	Free tier	First paid price
ConfigCat	Config downloads	10 flags · 5M downloads	$120/mo
DevCycle	Monthly active users	1,000 MAU	$625/mo
Flagsmith	API requests	50K requests · 1 seat	$45/mo
GrowthBook	Seats	3 seats	$40/seat/mo
Harness FME	Tracked keys + seats	Unpublished	Unpublished
LaunchDarkly	Server connections + MAU	Caps unpublished	$10/conn + $8.33/1K MAU
PostHog	Flag requests	1M requests/mo	Usage-based past 1M
Smpl Flags	Flags + environments	10 flags	$99/mo
Statsig	Analytics events	2M events/mo	$150/mo
Unleash	Seats	None - self-host the OSS core	$75/seat/mo

Prices are the vendor's published monthly-billing rate, verified against live pricing pages in August 2026. LaunchDarkly publishes only billed-yearly rates and no longer publishes its free-tier caps. Harness publishes no numbers at all. Smpl Flags' $599 Enterprise plan is the only enterprise price in this lineup that is both published and unlimited - at that tier even the flag meter is gone.

Targeting rules

Every vendor supports targeting rules over custom attributes (e.g. country, plan, email, anything you pass in). Where the vendors vary is how the rules are written.

Most give you a flat, ordered list of rules (i.e. OR across the rules, AND within one), maybe with a limit. If you need one rule that says “EU user AND (enterprise plan OR (beta tester AND version ≥ 3.2)),” only two vendors here support arbitrarily complex rules: GrowthBook, which uses Mongo-style conditions, and Smpl Flags, which uses JSON Logic. All other vendors will require you to break up complex expressions into multiple rules.

Service	Targeting rules	Arbitrarily complex?
ConfigCat	Flat rule list · 4 rules per flag on Free, 8 on Pro	✗
DevCycle	Flat rule list · reusable audiences	✗
Flagsmith	Flat segment rules · 100 conditions per rule	✗
GrowthBook	Nested AND/OR/NOT, Mongo-style conditions	✓
Harness FME	Flat if/else-if rule list	✗
LaunchDarkly	Flat rule list · up to 5,000 rules per flag	✗
PostHog	Flat condition sets, OR'd together	✗
Smpl Flags	Nested AND/OR/NOT via JSON Logic · 5 rules per flag free, unlimited paid	✓
Statsig	Flat rule list, first match wins	✗
Unleash	Flat strategies · 30 per flag per environment	✗

Environments

You will inevitably configure flags differently in different environments. Targeting rules that target anything by ID will almost surely vary since these IDs originate from different databases. So first-class support for environments is important - and just as important is the UX: the ability to “stare and compare” a flag’s configuration across environments on one screen.

Once feature flags are in the mix, if something is working in one environment but not the other, the answer may not necessarily be the code. It could just be a flag.

Two things to look for:

1. Environments exist as a first-class concept.
2. How many environments are included in your plan.

Service	First-class environments?	Environments on the FREE tier
ConfigCat	✓	2
DevCycle	✓	Unlimited
Flagsmith	✓	Unlimited
GrowthBook	✓	4
Harness FME	✓	Not published
LaunchDarkly	✓	3
PostHog	✗	-
Smpl Flags	✓	2
Statsig	✓	3
Unleash	✓	2

PostHog's documented pattern is a separate project per environment, with a copy tool to sync flag definitions between them. Unleash's open-source core fixes its two environments (development and production); creating environments is reserved for the paid product. Harness enforces environment limits but doesn't publish them.

Role-based security

This is something you probably won’t care about when you’re just starting out. Create a flag, write code against it, and then watch things light up by making changes in a console. But ship to production, and you quickly realize that every user that can configure flags can impact production, and most shops try to limit who can do that.

The feature to look for is generally referred to as role-based security (RBS), but it might be implemented as roles or groups. In either case, you’re looking for some way to either completely “hide” the production environment from certain users or restrict their ability to make changes to it.

Every vendor in this comparison supports RBS in one form or another, but it may not be included in their free tier.

Tracking changes

Ironically, the more you safeguard your features by flags, the more things might not work right if flags aren’t configured “just so.” So it’s important to be able to understand why a flag is configured a certain way: who last changed it and when.

If and when you find the change you want to revert, look for point-in-time restore. Otherwise, you’ll need to manually reconfigure the flag by hand.

Every vendor in this comparison keeps some change history, but it may be limited on their free tier: ConfigCat retains only 7 days and LaunchDarkly keeps only 30. Smpl Flags retains one year of change history starting at $99/month.

As for point-in-time restore, LaunchDarkly documents one-click restore of a previous version, Smpl Flags ships it on Pro and up, and ConfigCat’s audit log is explicitly read-only.

SIEM streaming

If you don’t know what a SIEM is, you can probably skip this section. For the rest of you: when a flag changes in production, your security team may want that event in Splunk or Datadog next to everything else.

There are two levels of support:

1. A change webhook POSTs to any HTTP endpoint you give it whenever flag configuration changes - which means it can reach any SIEM that ingests HTTP, with your plumbing in between.
2. A managed destination whereby the vendor formats and delivers change events to a named platform, no plumbing required. A vendor with a generic webhook can reach everything in the second column; the second column just tells you who does the work.

Service	Webhook on change	Managed destinations for change events
ConfigCat	✓	Datadog
DevCycle	✓	Dynatrace
Flagsmith	✓	Datadog, Dynatrace, New Relic, Grafana
GrowthBook	✓	-
Harness FME	✓	Datadog, Sumo Logic
LaunchDarkly	✓	Datadog, Splunk, Elasticsearch, Honeycomb, New Relic, Dynatrace
PostHog	✗	-
Smpl Flags	✓	Datadog, Elasticsearch, Honeycomb, New Relic, Splunk, Sumo Logic
Statsig	✓	Datadog
Unleash	✓	Datadog

The one miss: PostHog has no productized change webhook - flag changes land in its activity log, and getting them out requires wiring an internal event through its data-pipelines product by API. Everyone else will call your URL.

SDKs

On the server, SDK coverage isn’t a differentiator: every service in this lineup ships official server-side SDKs for all six languages we checked (Python, TypeScript/Node.js, Java, Go, C#/.NET, and Ruby).

In the browser, every vendor here ships a client SDK. smplkit’s is @smplkit/browser: a publishable read-only key scoped to a single environment, targeting rules evaluated locally in the page, and changes picked up over SSE with an automatic polling fallback. Identifying a user is a local recompute, not a network round trip.

Code-first, or configure-first?

Every vendor provides SDKs in the language of your choice that have methods that look something like this:

if flag_client.get("my-flag", False):
    execute_new_version()
else:
    execute_old_version()

In every case, you pass the default value to return if the flag does not exist or the client is misconfigured or the feature flag service is unreachable.

But for my-flag to actually exist for real, someone needs to go into the feature flag console and create it (or use an API or CLI or Terraform). Smpl Flags is the only vendor we know of that will actually create the flag by just declaring it in code:

flag = flag_client.flags.boolean_flag(
    "checkout-v2",
    default=False,
)

if flag.get():
    show_new_checkout()
else:
    show_old_checkout()

While this is a convenience, it’s more than that. It’s visibility. A configure-first system can’t tell you about the flags your code is referencing that you don’t know about - or forgot about. But if the vendor supports “code-first” methodology, when you log into your console and see both checkout-v2 and checkout_v2 showing up, you’ll know why the new version of your checkout process isn’t working.

Unleash does have something similar: its console lists “unknown flags” that SDKs requested but nobody created, exactly to catch typos and stale references. All other vendors will just silently return the default value.

Which should you pick?

By situation, because that’s how flags actually get bought:

If you want the safe, capable, everything choice: LaunchDarkly. It defined this category, and nothing else here matches its depth of targeting, governance, and integrations. You’ll pay for that on a meter that grows, at prices that mostly aren’t published - and plenty of teams decide it’s worth it.

If experimentation is the thing you’re actually buying: Statsig or GrowthBook - or PostHog, if you already live in PostHog. The flags come along for the ride; the stats engine is the purchase.

If you want to self-host: Unleash or Flagsmith. Both have real open-source cores. Unleash’s is the more battle-worn; Flagsmith’s paid tiers are the gentler upgrade path when you outgrow self-hosting.

If you’re a small team that wants a bill you can compute: that’s us. It’s the honest reason Smpl Flags meters flags and environments instead of your traffic - the two numbers in this lineup you can count and control. Seat-priced GrowthBook and Unleash are the next most forecastable.

Whoever makes your shortlist, test-drive two. Every service here has a free tier or a trial: wire up your real use case, flip some flags, and judge the console and the SDK ergonomics yourself - the one part of this decision no comparison table can do for you.