Cool! Feature flags are great when you need them. Iāve seen so many different implementations of flags over the years. Even made one myself couple years ago which uses a GitHub issue (and a list of checkboxes) as a persistent store for maintaining and toggling with flags. https://github.com/TimMikeladze/next-flag
This domain needs some better ontology and taxonomy, there's so many overlapping and conflated terms whenever I hear about it. To name a few:
- Feature Flags used as Configs;
- Configs used as Feature Flags;
- Live Ops, Control Groups, Experiments, Analytics, and more bundled as "extras" to Feature Flags as if they were the right parent term;
I think classical systems/engineering see feature flags as boolean state in some data store, but these PaaS are pushing it as a new thing and struggling with marketing.
I wish they took the gaming companies lesson and started using the term "Live Ops"
Had a look at their website [1]. Initial thoughts: this is a bit ridiculous, I can just build that myself. And in fact, I have done already.
Thoughts after about 3 minutes of browsing: OK, this actually makes sense and I see why people would pay for this. The value proposition is definitely there
I pay for it for my team... it's expensive to be honest, but worth it IMHO. Building it would be a ok, supporting it a pain.
If you work on a small startup, not worth it... on a Big corp with a lot of bureaucracy? It's worth it I think.
We have tried self-hosting it, but it's always a pain to allocate people on infra to do it, so I gave up and started paying for it for my teams, and they love it.
Thanks, "I could build that" ā "oh, that's what the other 90% is" is pretty much how Unleash started for us too. What does your homegrown version do? Always interested in where people draw the line between building and adopting.
I havenāt used unleash but itās pretty clear your characterization is wildly wrong. 30 seconds looking at docs shows it has features for gradual rollouts, A/B testing, experimentaion with analytics, authentication to control available features, and probably a lot more I missed in a quick skim.
Are most feature flag systems really just simple Boolean checks like this with no feedback loop? In 2009 Amazonās equivalent supported multi-variate flags (run test with more than 2 options), a feedback loop for performance/attribution, and
weighting. I donāt see any of that on the unleash home page, but also havenāt seen it in other feature config systems either.
What you are describing is usually part of analytics platforms (Mixpanel, etc.). A feature flag toggle only plays a small part in this (but it may also be used for a lot of other scenarios of how you may want to control feature flags).
Audience is decided by analytics tool -> Feature flag server maps audience to feature flag value -> Analytics tool tracks its events and includes feature flag value as attribute
We have automatically generated readouts that run hourly and daily, show metrics between control and variant across a ton of core business metrics, and we can even opt into measurement of some super esoteric stuff.
Granted we have a whole team supporting just that experimentation platform, but it's pretty cool. They even expose an MCP server for us to have agents do experiment analysis for us using.
A million monthly active users, even free ones, would cost you ~$10K/month on LaunchDarkly. A million sounds like a lot, but "active" can mean one visit, even anonymous users. ~$120K/year for feature flags is a ridiculous line item.
These SaaS companies are only valued this much because they charge based on MAUs, not request-based. I prefer PostHog's model. 100M requests/month is ~$2K [*].
Launch Darkly charges on volume across multiple dimensions, including MAU and server-side connections, plus log, trace and error counts. It's bonkers and anyone who can actually predict what it will cost (good luck) will run away as fast as they can.
There is no way a Feature Flag system is a multi Billion dollar company based on the tech, and if there IS a Saas-pocalypse it's coming for players like LD first.
Configuration as a Service companies must be a having a tough time these days...
I couldnt imagine a lot of teams are debating anymore whether to build their own or use an off the shelf product like this. The former being a straight forward task for an LLM. And the latter being a point of failure/attack for any one want to mess with the core foundations of a product.
Companies as well as people are still happy to pay for the second S in SaaS.
Building something, updating it, running it, testing etc. still requires resources and attention. One example for this would be taxis. You pay for the comfort of not having to drive the car, do maintenance, take into account road works, cleaning, etc. and not because you couldn't drive a car yourself. That time you can use instead to focus on your actual business.
At a certain scale (probably bimodal distribution) it makes sense to have a provider you can shrug it off to and point the finger to when things are missing features or the system goes down, etc etc. On the big-co end of that spectrum I think you are right and AI makes this stuff easy to launch internally.
The owner at my current gig has multiple times said "software is over" as it being a sort of gravy train of rent seeking. Products are gonna have to offer real / significant value to attract new customers. Maybe even to keep them, too...
>> and point the finger to when things are missing features or the system goes down
This sounds good in theory but - and I speak from experience with a FF system causing a system-wide outage - clients don't care why YOU had an outage, or that it's not immediately your fault, and they really shouldn't have to. The reality is more like you're paying for a dependecy that you can't mitigate.
Being able to point fingers is also a moot point from a theoretical perspective.
Given that every FF system comes with a bunch of different mechanisms that prevent your system from being catastrophically impacted in case the provider goes down, its still the fault of the integrating party if you experience an outage due to a FF provider.
Wow a server that can help you manage your booleans. That's so useful. Let me just add one more thing to my infrastructure so my list of booleans can be managed.
āopen sourceā but itās the nonfree AGPL, and naturally RBAC and SSO are behind a paywall. Iām tired of fake open source projects that just want the street cred and free marketing.
Donāt believe the hype. AGPL violates free software freedoms 0 and 1. It was designed by people who think that receiving a free gift confers obligation to reciprocate.
Unleash started in 2014 as an internal tool at my company at the time, because we wanted to ship to production continuously without big-bang releases. It's an Open-Source feature flag platform with SDKs for >25 languages.
A few design choices that might be interesting:
- Local evaluation: server-side SDKs fetch the flag config and evaluate in-process, so user data never leaves your app and a flag check is a memory lookup, not a network call.
- Shared Rust engine (Yggdrasil): the evaluation logic is written once in Rust and embedded in the SDKs, so behaviour is the same across languages.
- Unleash Edge: a Rust proxy/cache for frontend and edge clients at scale. (Commercial)
- OpenFeature: supported if you don't want to lock into our SDKs.
I can see using something mature if you are starting from scratch.
if you already are in a platform capture situation, eg. Azure App Configuration or AWS AppConfig where you already integrate with platform tools using the native auth primitives, what is the benefit one can expect from switching to unleash?
Cool! Feature flags are great when you need them. Iāve seen so many different implementations of flags over the years. Even made one myself couple years ago which uses a GitHub issue (and a list of checkboxes) as a persistent store for maintaining and toggling with flags. https://github.com/TimMikeladze/next-flag
This domain needs some better ontology and taxonomy, there's so many overlapping and conflated terms whenever I hear about it. To name a few:
- Feature Flags used as Configs;
- Configs used as Feature Flags;
- Live Ops, Control Groups, Experiments, Analytics, and more bundled as "extras" to Feature Flags as if they were the right parent term;
I think classical systems/engineering see feature flags as boolean state in some data store, but these PaaS are pushing it as a new thing and struggling with marketing.
I wish they took the gaming companies lesson and started using the term "Live Ops"
To me there two type of feature flag. For tech and not for tech.
If you have good CI/CD practices, an ENV for the environment has what feature is simplest. No new dependencies, change code commit deploy.
Non-tech folks need something else that allows them to switch it on and then off. For a variety of reasons.
Had a look at their website [1]. Initial thoughts: this is a bit ridiculous, I can just build that myself. And in fact, I have done already.
Thoughts after about 3 minutes of browsing: OK, this actually makes sense and I see why people would pay for this. The value proposition is definitely there
[1] https://www.getunleash.io/
I pay for it for my team... it's expensive to be honest, but worth it IMHO. Building it would be a ok, supporting it a pain.
If you work on a small startup, not worth it... on a Big corp with a lot of bureaucracy? It's worth it I think.
We have tried self-hosting it, but it's always a pain to allocate people on infra to do it, so I gave up and started paying for it for my teams, and they love it.
Thanks, "I could build that" ā "oh, that's what the other 90% is" is pretty much how Unleash started for us too. What does your homegrown version do? Always interested in where people draw the line between building and adopting.
Great comeback!
Hmm, after 5 minutes of browsing I still don't get it.
likewise this feels almost like a planted comment without any explanation. It's a get endpoint hosting some boolean fields.
Itās bad form to accuse people of being shills.
I havenāt used unleash but itās pretty clear your characterization is wildly wrong. 30 seconds looking at docs shows it has features for gradual rollouts, A/B testing, experimentaion with analytics, authentication to control available features, and probably a lot more I missed in a quick skim.
Which doesn't really explain why all the comments of the OP/author are flagged and dead... competition at work?
Are most feature flag systems really just simple Boolean checks like this with no feedback loop? In 2009 Amazonās equivalent supported multi-variate flags (run test with more than 2 options), a feedback loop for performance/attribution, and weighting. I donāt see any of that on the unleash home page, but also havenāt seen it in other feature config systems either.
What you are describing is usually part of analytics platforms (Mixpanel, etc.). A feature flag toggle only plays a small part in this (but it may also be used for a lot of other scenarios of how you may want to control feature flags).
Audience is decided by analytics tool -> Feature flag server maps audience to feature flag value -> Analytics tool tracks its events and includes feature flag value as attribute
usually some ādata scienceā team takes the results and decides what to do. really heavy process for something that is usually quite simple.
We have automatically generated readouts that run hourly and daily, show metrics between control and variant across a ton of core business metrics, and we can even opt into measurement of some super esoteric stuff.
Granted we have a whole team supporting just that experimentation platform, but it's pretty cool. They even expose an MCP server for us to have agents do experiment analysis for us using.
Attributing an event to a flag is a heavy process? Oof.
OpenFeature (https://openfeature.dev/) is very similar and backed by CNCF.
You can hardly compare an API specification with an implementing product. So, no, even if Unleash does implement OpenFeature.
Yesterday I saw that LaunchDarkly is a $3B company. How crazy is that?!
A million monthly active users, even free ones, would cost you ~$10K/month on LaunchDarkly. A million sounds like a lot, but "active" can mean one visit, even anonymous users. ~$120K/year for feature flags is a ridiculous line item.
These SaaS companies are only valued this much because they charge based on MAUs, not request-based. I prefer PostHog's model. 100M requests/month is ~$2K [*].
[*] I'm not affiliated with PostHog.
On Unleash Cloud: 100M request per month on Unleash cloud would be $235 + 75$ per seat ($53 Million requests included).
Launch Darkly charges on volume across multiple dimensions, including MAU and server-side connections, plus log, trace and error counts. It's bonkers and anyone who can actually predict what it will cost (good luck) will run away as fast as they can.
There is no way a Feature Flag system is a multi Billion dollar company based on the tech, and if there IS a Saas-pocalypse it's coming for players like LD first.
What would you recommend as an alternative?
Put flags in your own DB(s)?
Unleash Cloud ?
Shoutout to ConfigCat, https://configcat.com/
Same features as all these big guys, EU hosted, and down-to-earth pricing. Even the free tier got me quite far.
I'm unaffiliated btw.
Literally all their examples can be replaced by some sort of:
For frontend you add an endpoint that exposes this value.I guess their frontend for managing these is 'nice', but at the end of the day it's a static page that sets flags on redis.
The flags are often not static, though. Varies between environments, markets, user cohorts and whatever rules you can come up with.
What else do you need for feature flags?
> Release, experiment, and kill anything AI ships
The only appealing marketing I've seen in the past three years
Configuration as a Service companies must be a having a tough time these days...
I couldnt imagine a lot of teams are debating anymore whether to build their own or use an off the shelf product like this. The former being a straight forward task for an LLM. And the latter being a point of failure/attack for any one want to mess with the core foundations of a product.
Companies as well as people are still happy to pay for the second S in SaaS.
Building something, updating it, running it, testing etc. still requires resources and attention. One example for this would be taxis. You pay for the comfort of not having to drive the car, do maintenance, take into account road works, cleaning, etc. and not because you couldn't drive a car yourself. That time you can use instead to focus on your actual business.
At a certain scale (probably bimodal distribution) it makes sense to have a provider you can shrug it off to and point the finger to when things are missing features or the system goes down, etc etc. On the big-co end of that spectrum I think you are right and AI makes this stuff easy to launch internally.
The owner at my current gig has multiple times said "software is over" as it being a sort of gravy train of rent seeking. Products are gonna have to offer real / significant value to attract new customers. Maybe even to keep them, too...
>> and point the finger to when things are missing features or the system goes down
This sounds good in theory but - and I speak from experience with a FF system causing a system-wide outage - clients don't care why YOU had an outage, or that it's not immediately your fault, and they really shouldn't have to. The reality is more like you're paying for a dependecy that you can't mitigate.
Being able to point fingers is also a moot point from a theoretical perspective.
Given that every FF system comes with a bunch of different mechanisms that prevent your system from being catastrophically impacted in case the provider goes down, its still the fault of the integrating party if you experience an outage due to a FF provider.
You miss where the value of software is nowadays. Just the hosting of this thing is worse to pay for.
Analytics, documentation, configuration, etc saas companies must be having the same hard time.
Wow a server that can help you manage your booleans. That's so useful. Let me just add one more thing to my infrastructure so my list of booleans can be managed.
āopen sourceā but itās the nonfree AGPL, and naturally RBAC and SSO are behind a paywall. Iām tired of fake open source projects that just want the street cred and free marketing.
AGPL is as free as it gets. Perhaps the word you're looking for is non-permissive?
Donāt believe the hype. AGPL violates free software freedoms 0 and 1. It was designed by people who think that receiving a free gift confers obligation to reciprocate.
https://en.wikipedia.org/wiki/The_Free_Software_Definition
https://sneak.berlin/20250720/the-agpl-is-nonfree/
Hi HN, I'm Ivar, creator of Unleash.
Unleash started in 2014 as an internal tool at my company at the time, because we wanted to ship to production continuously without big-bang releases. It's an Open-Source feature flag platform with SDKs for >25 languages.
A few design choices that might be interesting:
- Local evaluation: server-side SDKs fetch the flag config and evaluate in-process, so user data never leaves your app and a flag check is a memory lookup, not a network call.
- Shared Rust engine (Yggdrasil): the evaluation logic is written once in Rust and embedded in the SDKs, so behaviour is the same across languages.
- Unleash Edge: a Rust proxy/cache for frontend and edge clients at scale. (Commercial)
- OpenFeature: supported if you don't want to lock into our SDKs.
I can see using something mature if you are starting from scratch.
if you already are in a platform capture situation, eg. Azure App Configuration or AWS AppConfig where you already integrate with platform tools using the native auth primitives, what is the benefit one can expect from switching to unleash?